For their fourth series, the Red Dwarf team entered movie-land as production shifted from the BBC's studios in Manchester (which were closed for refurbishment) to Shepperton Studios outside London.

With sets summarily transported down south, the cast were, for the first time, able to rehearse in the areas they would eventually shoot in. (Previous series had been rehearsed in Acton, with tape markings indicating the dimensions of the set.)

Added at the rear of Mel Bibby's set was a lengthy corridor. It doesn't sound like much, but with constant re-lighting this set gave Red Dwarf a sense of scale - it seemed there were always more areas to walk through. The corridor and the small piece of space it opened into were used over and over again in Series IV and V, forever looking just different enough.

One big change incorporated into Series IV was a tweak (or three) to the back-story. With the first two Red Dwarf novels - Infinity Welcomes Careful Drivers and Better Than Life - Rob Grant and Doug Naylor had tidied up some of the areas of the origin story they had since found a little unworkable. In Series IV, those changes made it into the TV show's universe.

From this point on, Red Dwarf belonged to the twenty-third century, not the twenty-first. (Not unreasonable, given how little outer-space colonising we've managed in the three years we've had so far!) The number of crew on a space ship five miles long was increased from 169 to 1,169 - with all but one dead, at least at this point they never had to hire the extras to create the illusion!

And Lister's history with his lost love, Kristine Kochanski, was changed to give the couple a full - if brief - relationship. For a short while they dated, before he lost her to a catering officer. In previous shows Lister had shared a grand total of 173 words with her - so things were looking up.

Series IV was filmed in the winter of 1990 and broadcast in February and March the following year. A cunning piece of episode juggling saw the Kryten love story Camille go out on Valentine's Day. Aaaah...

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