- Around 15,000,000,000 years ago, the previous Universe dies in a Big Crunch that becomes a Big Bang, creating the current Universe. A handful of ruthless, megalomaniacal cosmic beings survive by taking refuge in another dimension before the Big Crunch and re-emerging into this dimension after the Big Bang. They develop god complexes and go on to become known as the Great Old Ones.
- Around 5,000,000,000 years ago, the first indigenous sentient species in this Universe evolves on the planet Gallifrey. The existence of the humanoid Gallifreyans creates a morphogenetic field which gradually radiates across the Universe and encourages other humanoid beings to evolve on any world with a suitable environment. The Gallifreyans eventually master time travel and become the Time Lords.
- In the same era as the rise of the Time Lords, war breaks out between the militaristic clones of the Sontaran Empire and the crystalline shape-shifters of the Rutan Empire. The war will still be raging far into the future of the Universe. [If this sounds suspiciously reminiscent of the Kree-Skrull War, I’ve always suspected that it was ripped off from it.]
- Around 3,500,000,000 years ago, a race known as the Jagaroth destroy themselves and their homeworld in a civil war. A few manage to escape into space. One of their starships crashes on Earth and explodes. In some way, this creates life on Earth. [The date for this given on screen is actually only 400,000,000 years ago. We know from the fossil record that life existed on Earth long before that, so I’ve amended the date to reflect this.]
- An unknown length of time ago, the Universe reaches the point at which it should have totally succumbed to entropy according to the laws of thermodynamics. A race called the Logopolitans opens portals into other dimensions in order to draw extra energy into the Universe and avert this.
- By around 65,000,000 years ago, a race of sentient reptilian humanoids evolves on Earth. Their name for themselves in their own language is unknown, but they will one day become known as the Earth Reptiles. When the catastrophe that will cause the extinction of the dinosaurs occurs, they place themselves into suspended animation to wait until the environment will have recovered. Their technology subsequently malfunctions and they are left dormant for tens of millions of years.
- By around 100,000 years ago, anatomically modern humans evolve on Earth.
- Around 2,000 years ago, an all-powerful extradimensional energy being with the mental age of a child enters this dimension and creates a physical form for itself which is an imperfect copy of the planet Earth, complete with life and human inhabitants. This planet will become known as Mondas and its inhabitants will evolve into the cyborg humanoids known as the Cybermen.
- Around 1,500 years ago, a total war breaks out between the Kaled and Thal races on the planet Skaro, on the other side of this Galaxy. The war will last for a thousand years and devastate the planet with sustained nuclear, chemical and biological warfare.
- Around 500 years ago, the Kaled chief scientist Davros determines that his race is beginning to mutate into a new form of life adapted to the poisoned environment, whose final form will be that of an octopoid creature with a huge brain. He creates a number of such creatures which have been genetically engineered to remove their capacity for all emotions except hate and the urge to dominate. These are the first Daleks. When his fellow Kaleds attempt to bring a halt to his work, Davros betrays them to their destruction at the hands of the Thals before despatching the Daleks to destroy the Thals in turn. Before long the Daleks turn on Davros himself and seemingly kill him, although he actually survives in suspended animation. The Fourth Doctor is sent back to this period by the Time Lords to try to prevent the creation of the Daleks, but is unable to bring himself to do so because he considers that this would be genocide. History apparently remains unchanged.
- The Daleks eventually divide into two factions. One is content to rule Skaro unopposed, while the other is more ambitious and intends to expand into space. The latter constructs a space fleet and leaves Skaro, embarking on a program of conquering other worlds. The expansionists do not attempt to maintain contact with the stay-at-homes and the two branches of the Dalek race pursue separate destinies thereafter. All the while, the Daleks remain unaware that a small group of Thals has also survived in a distant part of Skaro.
- Around 1820, an off-course and damaged expansionist Dalek ship makes a forced landing on the planet Vulcan, which in the Doctor Who Universe orbits our Sun closer in than Mercury. [The story this occurs in was written at a time when some astronomers wrongly believed there might actually be such a planet. Star Trek probably took the name from the same source, although their Vulcan isn’t located within the Solar System.] Unable to take off again, the Dalek crew place themselves in suspended animation to await a rescue that never comes.
- During the 1950s the British Experimental Rocket Group under Professor Bernard Quatermass launches the first men into orbit years ahead of their American and Soviet rivals and becomes drawn into conflict with several different hostile alien forces.
- In 1963 the First Doctor visits Skaro for the first time and is inadvertently responsible for wiping out the stay-at-home Daleks there, but no word of their fate reaches the expansionist Daleks out in space at the time. The surviving group of Thals begins studying the Dalek technology and attempting to master its basic principles.
- During the 1960s Earth experiences several more alien incursions. One of these, in 1968, results in the formation of the United Nations Intelligence Taskforce or UNIT to defend against such threats. The British branch of UNIT is headed by Brigadier-General Alastair Gordon Lethbridge-Stewart.
- During the 1970s the British space program reaches Mars. The Americans and Soviets apparently establish permanent Moonbases around this time.
- In their first mission, UNIT thwart the first attempt to invade Earth by the Cybermen in 1970, aided by the Second Doctor. From 1970-73 the number of alien incursions reaches an all-time high, averaging one every few months. The Third Doctor is exiled to this period by the Time Lords and becomes the full-time Scientific Advisor to UNIT, beginning by aiding them in thwarting the first of a number of invasion attempts by the Nestene Consciousness and its armies of Autons. The frequency of alien incursions diminishes from 1973 onwards, averaging perhaps one per year for the rest of the 1970s. The Doctor is eventually pardoned by the Time Lords and his exile to Earth is lifted, but he continues to aid UNIT on a part-time basis until 1976, during which time he regenerates from the Third Doctor into the Fourth. All the while, the alien threat is concealed from the general public by UNIT and national governments.
- During this period the Earth Reptiles finally awaken from suspended animation and find that humanity has replaced them as the dominant species on Earth. They become divided into factions, one advocating peaceful coexistence while the other wishes to exterminate humanity and reclaim the Earth by force. Their existence is also kept secret from the general public by the human authorities. Amongst the few humans who do learn of their existence, they become known for a time by such names as Silurians and Sea Devils or simply as the Reptile People.
- The 1980s and 90s also feature alien incursions something like once per year. In 1986 the sentient planet Mondas, in need of more energy to sustain itself, returns to the Solar System and begins to drain energy from Earth. It consumes too much and destroys itself, taking most of the Cybermen with it. A few who had been out in space at the time survive.
- From the 2000s to the 2020s, the world is again beset by alien incursions something like once a year. The efforts of the authorities to conceal the threat finally fail and it becomes public knowledge. Especially notable amongst the incidents in this period are simultaneous invasions by Cybermen from a parallel universe and by Daleks from the far future of this universe in 2006, followed by the temporary displacement of the entire Earth to another part of the Galaxy by more Daleks from the far future in 2008. A growing realization of the need for humanity to unite against the common threat eventually results in the United Nations being restructured into a bureaucratic-technocratic world government known as the World Zones Authority. This is only a few years old when the Second Doctor is compelled to thwart a plot by the Mexican dictator Ramon Salamander to subvert it into a global tyranny under his rule.
- Perhaps in an effort to develop spaceflight technology that could have potential for defending Earth, an international colony is established on the planet Vulcan. The colonists discover the Dalek spacecraft that had crashed there two hundred years before and awaken its crew from suspended animation. The Second Doctor destroys the Daleks before they can multiply themselves into an army and conquer first Vulcan, then Earth. The colony is apparently abandoned soon afterwards, because it’s never mentioned again.
- Around this time, most of the Earth Reptiles commit themselves to peaceful coexistence and are cautiously accepted as neighbours by humanity. They begin actually using the name of the Earth Reptiles to describe themselves at this time.
- In the 2030s, humans make radio contact with aliens from the Arcturus System who give them the secret of matter transmission. The Travel-Mat Relay or T-Mat is established to transport people and goods around the world. Space travel is neglected and humanity thereby leaves itself vulnerable to more alien incursions. The Second Doctor thwarts an attempt by the Ice Warriors of Mars to invade Earth through the T-Mat network in the 2040s. After this humanity realize the need to permanently maintain spaceflight capability.
- The Cybermen make two more failed attempts to subjugate Earth in the 2060s and 70s. After this the Cybermen flee the Solar System.
- Humanity apparently develop faster-than-light drives and make some tentative explorations of other planetary systems beginning in the 2070s, but little comes of them at this time. The first alien race encountered during these expeditions are the instinctively timid and cowardly six-limbed natives of the Alpha Centauri System, with whom humanity establish peaceful diplomatic relations since they plainly pose no threat.
- For unknown reasons, national rivalries flare up again in the 2080s, with a new Cold War between rival blocs developing. A faction of renegade Earth Reptiles attempts to manipulate humanity into destroying itself in nuclear war but is thwarted by the Fifth Doctor.
- From 2088-90 humanity is forced to pull together again in order to fight the Thousand-Day War with the Ice Warriors. Humanity wins, in large part because of its ability to use military matter-transmission technology developed from T-Mat to instantaneously send reinforcements to any place where human forces have already established a bridgehead through conventional means. The Ice Warriors are also forced to flee the Solar System. Humanity finally learns its lessons about the dangers of disunity and remains united thereafter. Mars subsequently becomes a terraformed human colony and the T-Mat network is expanded into the Transit system, which enables instant teleportation between any two points from Mercury to Pluto.
- The fleeing Ice Warriors eventually colonize a planet near the Arcturus System, which is given the imaginative name of New Mars. They subsequently go looking for revenge on the Arcturans for having given humans the matter-transmission technology that proved so invaluable to them in defeating the Ice Warriors in the struggle for dominion over the Solar System. Centuries of periodic armed conflict and bitter hatred between the peoples of New Mars and Arcturus are the inevitable outcome.
- Humanity embark on full-scale interstellar colonization efforts in the 2110s, when population pressure on Earth begins to tell. By this time human society has become completely globalized, with the apathetic materialistic masses ruled over in theory by self-serving elected politicians but in practice by an unaccountable technocratic bureaucracy. The colonies established in other systems largely fall under the domination of over-mighty interstellar corporations, which the authorities can do little to keep in check. The corporations become the dominant force in human society for the next several centuries.
- In the 2150s, a Dalek task force operating at the extreme limits of its range bypasses the human colony worlds and attacks Earth using biological warfare, wiping out most of its inhabitants. The few survivors become slaves, labouring on a grandiose Dalek project to convert the Earth into a planet-sized mobile fortress to be used in conquering the Galaxy (something like the Death Star, by the sound of it). The First Doctor sabotages the project and leads the overthrow of the Daleks in the 2060s. Because of the logistical difficulties involved in mounting another such expedition when the colony worlds will now be alert to and armed against the threat they pose, the Daleks do not attempt to re-conquer Earth at this time.
- In the 2180s and 90s, the regrouped Cybermen take advantage of the disarray the Daleks have thrown humanity into by seeking to conquer the colony worlds in the First Cyber War. They lose and are again driven close to extinction in consequence.
- Since the colony worlds are preoccupied with the threat from the Cybermen, Earth is left to recover from the Dalek occupation as best it can for at least a generation before the colonies make any effort to step in and help. Eventually it gets rebuilt along much the same lines as before, being rapidly repopulated by people re-immigrating from the colonies. The colonial governments and interstellar corporations apparently still regard Earth as having some value as a neutral arbiter in their disputes, since they allow it to re-establish a considerable military force. This ends up coordinating the efforts of humanity as a whole in several additional interstellar wars against hostile aliens which are fought over the next few centuries.
- In the 24th Century, the renegade Time Lord Morbius recruits an army of barbaric mercenaries and attempts to conquer this Galaxy. The Time Lords assemble a grand alliance of its major powers to oppose him, with humans, Cybermen and Sontarans amongst those participating. The alliance is victorious and Morbius is captured and executed.
- In the 25th century, the Second Doctor thwarts an attempt by a faction of logic-worshipping renegade humans to revive a force of Cybermen who have been in cryogenic hibernation on the planet Telos for centuries. But the Cybermen are only kept dormant rather than being destroyed.
- In the early 26th Century, the hibernating Cybermen are finally revived by another force of Cybermen which has been lurking out in space for centuries. The two groups merge and begin gearing up for another war. The subsequent Second Cyber War forces humanity to become more unified than before in order to survive and prevail. Yet again, the Cybermen are driven close to extinction.
- A decade later, humanity is compelled to forge an alliance with alien rivals such as the Draconian Empire against the even greater common threat of the Daleks. The Dalek Wars rage for over three decades and claim the lives of half of the human race before the Daleks are finally defeated. The colony worlds and the interstellar corporations are forced to subordinate their military forces to the authority of the Earth military under the banner of the Terran Federation and accept a huge increase in the powers over them of the Earth government, which becomes a military-political dictatorship accustomed to ruling by decree. These powers are not relinquished when the Wars end and the dictatorship progressively evolves into a monarchy, creating what historians will later refer to as the First Human Empire. Its first monarch is a former President of the Terran Federation who renames herself the Divine Empress, Glory of the Human Empire.
- Meanwhile, the few surviving expansionist Daleks are left confined to a small core territory. They belatedly attempt to renew contact with the stay-at-home Daleks on Skaro, only to learn that they’ve been extinct for centuries and that the planet has been under the control of the Thals ever since. By this time, the Thals have developed space travel and learned of the continuing Dalek threat from space. Knowing that they could not hope to defend their homeworld from a determined Dalek effort at reconquest, the Thals have already completed the evacuation of Skaro and colonized a new world far away. The expansionist Daleks re-occupy Skaro themselves unopposed.
- Around the beginning of the 27th Century, the Daleks attempt to avenge their defeat by unleashing biological warfare on the rest of the Galaxy but are thwarted by the Third Doctor.
- The Human Empire eventually turns on former allies such as the Draconian Empire and conquers them. By the 29th Century it rules half of the Galaxy and has no serious rivals left to challenge it. Along the way it has re-created the system of aristocratic titles and privileges and re-incorporated neo-feudal elements into its culture. The Divine Empress Helen I, who ascends the throne in the early 29th Century, extends her reign and her lifespan far beyond their natural limits through the use of artificial life-support systems incorporated into a prosthetic throne, which is capable of instantly teleporting her to any part of her far-flung domains and back.
- As the Human Empire grows, the Earth Reptiles are carried out into the Galaxy with the wave of human expansion and form minority communities of their own on many human colony worlds.
- In the late 30th Century, the Human Empire falls apart from overstretch. By this time, the Divine Empress Helen I no longer enjoys even the limited mobility previously afforded her by her teleporting throne. She is now confined to immobile life-support systems at the core of a space station in the outer Solar System, her brain hardwired into the vast computer system that coordinates the functioning of the entire Empire.
The Human Empire effectively comes to an end when the Divine Empress finally loses the will to live and commits suicide by sabotaging her own life-support systems. The computer system progressively breaks down completely in consequence and coordinating the functioning of a vast interstellar realm becomes impossible for her former minions. The Empire rapidly breaks up into a number of smaller interstellar alliances and countless independent worlds. Most of the alien races humanity had subjugated regain their freedom. An opportunistic attack on the Solar System by a feeble remnant of the Cybermen fails despite the chaos.
Without the immense material resources of the Empire at their disposal, the population of Earth are unable to maintain the advanced technology that artificially sustains the planetary environment, which their ancestors had long ago ravaged to the point where the natural biosphere collapsed. Mass famine results in countless deaths before emergency aid from other worlds reaches the Solar System. Earth itself is briefly plunged into a new Ice Age, but an intensive crash research programme yields a technological fix to the problem. The planet nonetheless remains an economic and political disaster zone for the next century.
Since it seems almost inevitable that any aliens who were resident on Earth when the Empire fell would have been attacked by human mobs looking for scapegoats to blame for its fall, it can reasonably be assumed that those who escaped the pogroms fled from the Solar System. The same kind of backlash may have affected the Earth Reptiles as well, forcing them to abandon their beloved homeworld at last there are no known references to them living on Earth after this period. Eventually the human population of Earth painfully re-learns how to re-establish a functioning society with only the depleted resources of a single planet at its disposal. Terraforming technology is used to re-create much of the natural biosphere.
- Around the beginning of the 32nd Century, improvements in faster-than-light drives enable humans seeking an escape from the turmoils of this Galaxy to set out for other Galaxies in search of colonizable worlds where they can live a quieter life. The Daleks likewise broaden their field of operations and begin sending out long-range expeditions to other Galaxies. One Galaxy is eventually completely conquered by them, becoming the new focus of most of their operations. They later take the final logical step of transferring their capital there and leaving most of their remaining territory in this Galaxy occupied only by a minimal garrison force. Skaro is considered of such little value that it’s abandoned completely.
- Around the beginning of the 35th Century, a bureaucratic Galactic Federation similar to the present-day UN is formed, with its capital on Io, one of the moons of Jupiter. Various human interstellar alliances and independent worlds join on an equal basis with various alien ones, creating a human preponderance in terms of total population. Notable among the alien races joining are the Ice Warriors and the Arcturans, who finally resolve to forge a lasting peace between their peoples.
- Around the beginning of the 40th Century, the Galactic Federation is forced to fight an intergalactic war with the Fifth Galaxy, ultimately prevailing despite the treachery of renegade humans and Ice Warriors who are secretly working for the enemy. Also around this time, the Daleks renew their interest in the Galaxy of their origin. They reoccupy Skaro again and reinforce their garrison forces in the rest of their holdings here. It may be at this time that the Daleks first begin to master the principles of time travel.
- At the beginning of the 41st Century, the Daleks forge an alliance with a number of other totalitarian regimes ruling neighbouring Galaxies to invade and conquer this Galaxy. They secretly plan to turn on their allies once their forces are committed and attack them from the rear, destroying them and conquering their Galaxies as well as this one. The Daleks are also being aided by human traitors within the Galactic Federation. This master plan is foiled by the First Doctor and the Daleks are deserted by their allies after their intended treachery is exposed.
In sheer frustration, the Daleks alone subsequently launch an all-out frontal attack on this Galaxy regardless. They are eventually repelled, but the Galactic Federation is forced by the pressures of war to restructure itself into a human-dominated military-political dictatorship which does not relinquish its power when the war ends. In all but name, it subsequently becomes the Second Human Empire. This time the despotism will last for thousands of years. At some point the capital is apparently moved from Io to somewhere more centrally located in the Galaxy, leaving the Solar System a political and cultural backwater.
- From the 44th to the 46th Centuries, the Daleks become locked in a stalemated war with a race of humanoid androids called the Movellans. Somehow they come up with the idea that studying the original research of their creator Davros may help them to improve their capabilities enough to give them victory. They return to Skaro to excavate the ruins of his laboratory and find Davros himself still alive in suspended animation. Davros is revived and subsequently embarks on a long struggle to reassert control over his creations.
Along the way the Daleks lose their war against the Movellans when the kind of biological warfare they have frequently used against others is turned against them. In the 47th Century the First and Second Dalek Civil Wars are fought and the supporters of Davros ultimately lose to the supporters of the first recorded Dalek Emperor. Davros is placed back into suspended animation rather than being killed in case the Daleks should have any future use for him.
- This era also sees the Daleks once again engaged in attempting to conquer territory in this Galaxy. Humans, Draconians and the Thals are prominent amongst the races resisting them with vigour. These efforts on the part of the Daleks are also eventually thwarted by their enemies. This is the furthest point into the future at which the Thals are known to still survive.
- Rendered irrelevant to the affairs of the Galaxy as a whole, Earth eventually sinks into a nostalgic torpor obsessed with its perceptions of past glories. Long-obsolete national and cultural differences are rediscovered (or reinvented) and gain renewed importance to the point where no fewer than four World Wars are fought by the end of the 50th Century. In the aftermath of the devastating Sixth World War, a new wave of interstellar colonization sees refugees from an exhausted Earth leaving their homeworld in search of new lives on new worlds. Since most suitable planets in this Galaxy have already been colonized long ago, they are generally forced to keep moving and travel on to other Galaxies to find vacant worlds they can occupy.
- In the 51st Century, the Daleks experiment with restoring the capacity for emotions such as compassion to a group of Dalek test subjects, intending merely to better understand how these emotions work in order to better exploit the weaknesses of their enemies. In the event, the test subjects soon come to regard themselves as a new breed of Dalek and refuse to remain subject to the old breed. The Third Dalek Civil War results. It claims the life of the first Dalek Emperor before ultimately ending in victory for the old breed, with the new breed apparently being exterminated.
- An unknown length of time into the future, the Daleks ultimately challenge the Time Lords of Gallifrey themselves for universal domination and the two races annihilate each other in the cataclysmic Time War, in which the Eighth Doctor plays a key role. The second recorded Dalek Emperor and a small retinue escape destruction by fleeing into the distant future. Another force of Daleks escapes by fleeing into another dimension and eventually re-emerges into this dimension back in the 21st Century, where they will be responsible for the Dalek invasions of Earth recorded in 2006 and 2008.
- The Galactic Federation (which will often be referred to by later historians as the Second Human Empire) ultimately disintegrates in a series of brutal civil wars thousands of years from now. Afterwards Galactic history seems to become uneventful for thousands of years more, with no major wars recorded. It is known that both Earth Reptiles living in minority communities on human-colonized worlds in the Galaxy and Cybermen who have finally outgrown their warlike past still survive in this era.
- Around 10,000 years from now may be the timeframe in which the BBC TV series Blake’s 7 is set. (See Longish Footnote below.)
- An uncertain length of time into the distant future (I once estimated it for my own purposes as around 15,000 years from now) the Sun enters a period of instability and solar flares render the worlds of the inner Solar System uninhabitable. A select group of volunteers are placed into suspended animation aboard a space station in the outer Solar System to wait until Earth should become habitable again. Other volunteers embark on another wave of intergalactic colonization. Most of the population simply perishes.
- The sleepers will hibernate for 10,000 years before finally awakening to repopulate their homeworld (by my calculation this occurs around 25,000 years from now). The Fourth Doctor saves them from being consumed by alien parasites known as the Wirrn and also prepares the ground for their return to Earth by destroying a Sontaran outpost there.
- By around 35,000 years from now, humanity is widely dispersed across a number of Galaxies and Earth is a barely-remembered legend to most people. New human military powers such as the Morestran Empire function independently without displaying the slightest interest in the world, or even the Galaxy, of their remote ancestry.
- At some point a Third Human Empire rises and falls under unrevealed circumstances. Whether Earth is ever its capital or not is unknown.
- By around 198,000 years from now, the Fourth [Great and Bountiful] Human Empire is at its height. How it arose and how it eventually falls are both unknown. The second Dalek Emperor and its retinue re-emerge in this era and attempt to subvert the Empire to their own purposes by genetically re-engineering cells extracted from many abducted humans to create new Daleks. They are eventually exposed and destroyed 200 years later thanks to the efforts of the Ninth Doctor and his companions.
- Around 2,000,000 years from now, Earth is again devastated by solar flares. It eventually recovers again.
- Around 10,000,000 years from now, the Sun becomes unstable for a prolonged period of time or perhaps permanently. The population is again evacuated to other worlds. Whether Earth is ever repopulated again after this is unknown.
- Around 5,500,000,000 years from now, the Sun dies and the long-uninhabited Earth is destroyed with it. By this time a planet with the imaginative name of New Earth has long since become the home of the descendants of its last inhabitants.
- A very long time indeed into the future, the last stars in the Universe burn out and it becomes a lifeless void. The last desperate, dying remnants of humanity degenerate into psychotic, senile cyborgs known as the Toclafane before at last becoming mercifully extinct. Finally the entire Universe is destroyed in a Big Crunch which gives rise to a new Big Bang, creating a new Universe with its own future stretching ahead of it. But that’s another story.
The classic BBC TV series Blake’s 7 has also been declared to be part of the same fictional universe as Doctor Who. If you’ve never heard of it, it ran for four seasons from 1978-81 and featured the ultimately-doomed struggles of a group of seven freedom fighters led by a man named Blake against the tyranny of the fascistic Terran Federation, headed by the dictatrix Servalan.
Their early nemesis in the field was Space Commander Travis, who was killed midway through the run after attempting to betray the human race to alien invaders from another Galaxy. These were originally going to be the Daleks, but the filmed version of the story replaced them with jellyfish-like creatures. The Federation had been created after a previous society had been largely demolished by an Atomic War involving much of the Galaxy centuries before.
It was never made clear how far into the future Blake’s 7 was set, since the Federation had started a new calendar after it was founded. Most of the worlds visited by the main characters were inhabited by humans or humanoids, but it was unclear whether all of these were descended from colonists from Earth or whether some of them were true aliens.
Those whose ancestors definitely had come from Earth often dismissed the traditional accounts of their origins as a myth, suggesting that their worlds had been colonized long before living memory. There were other human interstellar alliances besides the Federation, which was still some way off from achieving its goal of Galactic supremacy. One of these was called the United Planets.
The name of the Terran Federation had previously been applied to Earth and its colony worlds as early as the 24th Century, so the use of the name in the time of Blake and company is obviously a reversion rather than an innovation. There really isn’t much clue from that or from anything else as to just where to place Blake’s 7 within the overall chronology above.
FWIW, my guess would be that it’s sometime after the fall of the Galactic Federation (or the Second Human Empire) thousands of years from now. It certainly has to be long before Earth is rendered uninhabitable for the first time by solar flares around (by my calculation) 15,000 years from now. For a conveniently round figure, setting Blake’s 7 around 10,000 years from now might work. The overall technology level seems rather low for that, but that’s true for most Doctor Who stories set that far into the future as well.