S4 - Checkmate

When you look at all the episodes of Doctor Who ever made, it is actually difficult to find many installments that changed the entire direction of the programme. Checkmate is one of those episodes.

Up until now, The Doctor has been from some mysterious race and an unseen planet, with only his granddaughter as proof that anyone else from his kind even exists. In Checkmate, we find out that not only does The Monk have a TARDIS of his own, but he is a member of The Doctor's race. The Doctor is no longer unique, and neither is his time ship. It could have been dangerous to introduce this into the history of the show, as it may have reduced the amount of mystery and intrigue in its title character. Instead, it just increases the questions. We don't know at this point why The Doctor left his home planet, and we now must ask why the Monk did the same thing.

Also, this story features the birth of the "psuedo-historical". In previous stories set in Earth's past, The Doctor has been there almost purely as observer of actual events, forbidden to interfere. With The Time Meddler, the main antagonist is also someone from outside of time and place where the story is occurring, and, as opposed to past events being characters unto themselves in "true historicals", the location of the story is now merely a backdrop to a bigger story going on around it. We wouldn't see the complete transformation from "true" to "psuedo-" for another couple of seasons, but the seeds were most definitely sown here.

The Time Meddler is often overlooked, and undeservedly so - it is a delightful little story. The last episode, and the season, ends with poetic closeups of The Doctor and his companions staring out at the stars, perhaps staring off to the changes and challenges they will face in Season 3...