Arriving in London 1966, the Doctor feels an evil force pulling him towards the Post Office Tower. It is WOTAN – a super-computer so clever that, unbeknownst to its creator Professor Brett, it has developed an intelligence of its own. Taking over those around it using hypnosis, WOTAN begins construction of a fleet of War Machines to subjugate the world. The First Doctor was able to capture a War Machine, reprogamme it and send it back to the Tower to destroy WOTAN.
Of the First and Second Doctor’s 253 episodes, only 147 are held complete by the BBC. It may seem difficult to understand why this happened to such a well-loved programme, but it was part of the way television was made at the time.