I was lucky enough to hear this story recently, thanks to Tim letting me have the old BBC cassette release. Even allowing for Eric Saward's appalling narration, the quality & atmosphere of the story shines through. The story itself has a real sense of claustrophobia to it, with these people virtually stuck in this one small colony, and with the Daleks slowly taking over - the fact that the audience knows the Daleks are evil, while the characters don't, is a master-stroke of writing, and gives moments such as the "I am your servant" cliffhanger a real double-edge.

As for Troughton himself, heaven knows what viewers in 1966 thought. So different to Hartnell in his prime, it's an intriguing characterisation, and Troughton gives it a definite charm and appeal. He seems rather remote and distant with regards to his companions, I think, acting as a bit of a loner, and that gives the story yet another level to it, with the viewer perhaps being invited to side with Ben, whose suspicions of this newcomer remain for some time.

I always find it interesting that the BBC seemed to so downplay the new Doctor - the radio times has the Daleks on the cover, with no mention of a change of lead; and even the recently-discovered trailer doesn't refer to it (although personally "Ben, Polly - come and meet the Daleks" sends a thrill up my spine every time I hear it). I suppose that indicates just how uncertain they were that the changeover would work - and it's a real testament to a combination of good scripting, and good acting, that it does succeed so well.