BBC1 premieres the 27th episode of Terry Nation’s science fiction series Blake’s 7. This episode kicks off the third season and a running story arc through the third season regarding the Federation’s severe loss of manpower and territory during the intergalactic war that happens off-screen between seasons. Josette Simon and Steven Pacey are introduced as new guest stars, and Paul Darrow as Avon is established as the show’s new lead actor. Richard Franklin (Doctor Who) guest stars. 
BBC1 premieres the 28th episode of Terry Nation’s science fiction series Blake’s 7. This episode continues the story arc of the Federation’s postwar rebuilding. Michael Sheard and John Hollis (both of whom will be seen later in 1980 in The Empire Strikes Back) guest star.
BBC1 premieres the 29th episode of Terry Nation’s science fiction series Blake’s 7. This episode focuses heavily on new series regulars Josette Simon and Steven Pacey; Michael Gough (Batman) guest stars.
BBC1 premieres the 30th episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 31st episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 32nd episode of Terry Nation’s science fiction series Blake’s 7. Colin Baker (Doctor Who) and Valentine Dyall guest star.
BBC1 premieres the 33nd episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 34th episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 35th episode of Terry Nation’s science fiction series Blake’s 7. This episode, written by fantasy novelist Tanith Lee, is unique in that it features only the regular cast with no speaking guest stars.
BBC1 premieres the 36th episode of Terry Nation’s science fiction series Blake’s 7. This episode is written by novelist Trevor Hoyle, who has already penned two Blake’s 7 tie-in novelizations during the series’ first season.
BBC1 premieres the 37th episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 38th episode of Terry Nation’s science fiction series Blake’s 7.
BBC1 premieres the 39th episode of Terry Nation’s science fiction series Blake’s 7, ending the third season and seeing out series regular Jan Chappell (Cally) and the Liberator. This is the last script written for the series by Terry Nation, as he has decided to try his fortunes as a writer and producer in Hollywood, and is intended to be the series finale. When broadcast on the BBC, a voice-over on the end credits informs viewers that Blake’s 7 will return in 1981 – something that even the cast and crew aren’t aware of until then. Gareth Thomas guest stars as Blake.