Which British sci-fi series featured characters Kerr Avon, Jenna Stannis and a portable computer called Orac?

Player #14993519. , Blake's 7 was a low-budget BBC sci-fi series that was written to compete with Star Trek - a high-budget US sci-fi series. Critics were scathing about the wobbly scenery and cheap gravel-pit sets. However, the script and the storylines were brilliant, and the show is a monument to what can be done with almost no money. It's well worth watching. You can find the whole thing on YouTube but you might have to dig around to find the final episode. Really the script is what makes it - full of subtlety and off-beat humour.

Player #29100022, I agree, loved watching it as a kid. I particularly liked the villain, a woman called Servilland, a Federation commander.