4B2 - The Sontaran Experiment 2

The Sontaran Experiment is a trite little two-parter (the only two-part story in the whole of the 1970s) that serves the function of breaking up the two juggernaut stories on either side of it while providing diverting entertainment to the masses. It's also, at 46 total minutes, one of the better paced stories of its day, and one that stands up rather well to the 45-minute episodes of the new series.

However, this story signals a change in philosophy in the production of the show. For the past several seasons, there had been, for the most part, a fairly even mix of four-part and six-part stories, although the latter outnumbered the former during the Jon Pertwee era. The Sontaran Experiment and The Ark in Space were, in essence, a six part story in production terms, as the same crew performed as much location work as is usually done on your average six-part story for Sontaran, then retired to the studio to record the normal amount of material for that six-part story.

Splitting a six-part production into two stories, though, showed how Philip Hinchcliffe and Robert Holmes were not fans of the six-part story format, and were keen to move away from them as much as they could. As it would happen, there would only be three six-part stories in the Hinchcliffe area, and two of those would have been structured by Holmes in a similar way to Sontaran/Ark was. In moving to six overall stories (eventually) in a season, it also showed how much more confident the BBC was in Doctor Who by shelling out more money to produce different sets and costumes for six stories instead of five.

Flush with more money and more confidence, The Sontaran Experiment, a quiet little two-part diversion on the inside, is actually a major signpost of what was to come.