why is there no sexual tension on the Liberator ?

Sarcophagus. They'd probably all be dead if Avon hadn't put the moves on Cally to get the ring away from her.

Different times, really. Back then, most SF films or TV series had little or no sexual tension - even in Star Wars, with Han Solo and Luke Skywalker both trying to impress Princess Leia, it was very much kept in the background, secondary to the special effects and action. Star Trek (the original cast) just didn't go there either, if you think about it, apart from very isolated incidents, and nor did Alien - whatever might have been going between Ripley and Dallas in the past, for example, was pretty much edited out. It's the same with SF novels at that time - any romance is pretty conventional and kept very much in the background, because the perception was that SF fans were more interested in the SF elements - Space, Aliens, Time Travel etc - than the Boy Meets Girl thing (which was probably true). The writers of Blake's 7 realised that, given the claustrophobic conditions aboard the spaceship, any relationship was going to lead to friction and conflict amongst the crew, and they just didn't want to go down that road at all.

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