I love how this episode is nearly all exposition, but it’s more entertaining than all the running around quarries in Destiny of the Daleks. While the Count and Countess act like they’re in Hustle and explain their clever plan to pinch the Mona Lisa, the Doctor gets locked in a cellar but still manages to learn about the Count’s time experiments and uncovers six copies of Leonardo’s masterpiece before he escapes. It’s then a short hop back to the Renaissance for another twist cliffhanger (I like these a lot better than the normal “Dr Who is about to be exterminated!” ones). Last time it was “The Count is a monster!” this time it’s “The Count is a time traveller!”

Tom Baker is great, but I love the rivalry between the Countess and Romana as much as the Doctor’s polite sparring with the Count. The Countess is wonderfully condescending about the Chinese puzzle box, and Romana takes the bait, giving her a defiant little smile and proceeding to prove her wrong. The Doctor may be happy to play the fool, but no-one gets away with treating Romana like an idiot. In general, the character work is brilliant: the Doctor’s attempts to make small talk with Hermann gets short shrift. Duggan has wandered in between three alien geniuses and has nothing to contribute but his fists – with the joke that, despite the Doctor’s tutting, every time he muscles in it’s helpful, fixing the sonic screwdriver, breaking into a secret chamber, and putting the Count out for the count.

I’m also “stanning” the jokey kisses to the past, and specifically the Pertwee years. The Doctor gets to reverse the polarity and de-age a (mother) hen, and he offers Duggan the job of scientific advisor. Steven Moffat’s entire Doctor Who catalogue is essentially riffing on this blend of smart dialogue, clever exposition, cheeky continuity references and casual time-travel.

Next episode: City of Death – Part Three