First broadcast in January 1978, Blake's 7 was created by Terry Nation, the man behind Survivors and responsible for the Daleks in Doctor Who. However, unlike Star Trek, its distant American cousin, the weekly episode of Blake's 7 didn't consist of a cosy space adventure with a group hug at the end; this was an unashamedly British piece of science fiction. The good guys, if a group of criminals could be called good guys, didn't always win, often escaping with their lives and little else.

Led by Roj Blake, the crew of the highly advanced Liberator was made up of Kerr Avon, a computer expert; Vila Restal, a thief with a talent for opening any lock in existence; Cally, a telepath from the planet Auron; Jenna Stannis, a smuggler; and Olag Gan, a man who killed a Federation guard after his girlfriend was murdered. The seventh member of the crew was Zen, the Liberator's main computer.

After the initial four episodes that introduced the members of the crew (novelised in Blakes' 7), the episodes were generally standalone stories, although many of them featured Servalan, the Supreme Commander of Space Command, and Travis, the Space Commander whose only goal in life was to kill Blake.

A two-part story spanning Seasons One and Two saw the introduction of Orac, the arrogant supercomputer. Several episodes later Gan was killed during another futile attack against the Federation; more proof, if any were needed, that Blake's 7 was prepared to break the rules. At this point in time the only major character to be killed off in a British science fiction series had been Toby Wren in Doomwatch, although that, perhaps, had more impact as Wren was far more central to the story-telling than Gan had ever been.

As Season Two progressed, Blake's fight against the Federation changed slightly as he started searching for Star One, the Federation's communications centre through which all their transmissions were channelled. The season concluded with Travis betraying our galaxy to the Andromedans. With the Liberator leading the front line against the invaders, Blake was forced to contact the Federation, unable to hold off the invaders without help. The closing scene of Star One saw the first shots being fired in an intergalactic war.

Season Three began with the Andromedan space fleet being eliminated. In the process, Star One had been destroyed and the Liberator was seriously damaged. The crew use the escape pods and, over the first two episodes, have to find their way back to the ship. Gareth Thomas and Sally Knyvette, who played Blake and Jenna, had left the series between seasons so their places on the crew were taken by Del Tarrant, a former Federation pilot, and Dayna Mellanby, a weapons expert. Now under the command of Avon the crew continued their adventures but by the end of the season they would find themselves stranded on the artificial planet Terminal - the Liberator having been destroyed in orbit. This was originally intended to be the end of Blake's 7, but at the twelfth hour a Season Four was unexpectedly commissioned and, much to surprise of the cast and crew, announced over the end credits of Terminal.

With the Liberator destroyed a replacement had to be found, and in the opening episode of Season Four Avon hijacked the Scorpio, a battered freighter. Its owner was Dorian, who turned out to be a two-hundred year old who was kept young by a monster in cavern below his base on the planet Xenon. With Dorian's death the survivors of the Liberator acquired both a new ship and a base of operations. Original crew member Cally had been killed off-screen at the start of the episode and was replaced by Soolin (Glynis Barber).

The final episode of Blake's 7 was, appropriately enough, entitled Blake and has gone down in television legend for being the episode which apparently killed off all of the regular characters (apart from Servalan) as well as Blake. As the credits began to roll only Avon was still standing, and the ambiguous sounds of gunshots over the credits suggest that even he had finally met his end.

Since the final episode was broadcast in 1981, several original novels have been published. Afterlife by Tony Attwood took up the story from the conclusion of Blake, and Avon: A Terrible Aspect by Avon actor Paul Darrow took the opposite approach by chronicling Avon's life up to the beginning of the television series. Neither of them is held in high regard.

The continuing popularity of the series has also led to two radio serials being produced for BBC Radio 4. The Sevenfold Crown and The Syndeton Experiment were both written by former Doctor Who producer Barry Letts and are, if anything, even worse than the two original novels — any similarity to the television series being purely coincidental! Both stories have been released on CD.

In recent years the rights to Blake's 7 have been acquired by Blake's 7 Enterprises, with plans announced to produce audio stories, a CGI cartoon series and a new live action drama. So far their only noticeable actions have been to prevent an already filmed documentary from being included on the DVDs and to fall out with Paul Darrow...

All four seasons of Blake's 7 have now been released unedited on DVD.