The reveal that the bandaged creature in the mummy’s tomb is actually the Monk is a great, if very obvious, pay-off to the previous cliffhanger – and Butterworth’s ‘monky-business’ is huge fun, especially when he turns a corner of the pyramid and walks straight into a Dalek patrol. His desperate improvisation (and Beatles hair) is practically the second Doctor a year early. Our last glimpse of him, stranded on a planet of ice, is suitably sequel hunting. It’s a shame that never happened, however given the similarities in characterisation it’s hard to see him working as such a good foil against Troughton. But up against Hartnell – here at his most imperious when he’s negotiating for the release of the Dalek hostages – he’s perfect.

Chen is also getting desperate, furiously slapping away a Dalek’s eyestalk and shaking the captive Monk by his habit while angrily demanding the Taranium Core. The cool control of the earlier episodes has slipped – until he gets the Core back, and the old high-handedness returns.

The Daleks themselves are largely in the back seat, although they do get one killer moment: ‘One Dalek is capable of exterminating all!’, a line RTD must have remembered when writing Doomsday 40 years later.

Largely concerned with plot mechanics (writing out the Monk and the comic elements of the story; tipping the balance back in the Daleks’ favour to raise the stakes ahead of the final showdown, and giving the Doctor a means of directing the TARDIS to Kembel), this is a fairly unremarkable 100th episode – a milestone that gets no fanfare in the story.

Next episode: The Abandoned Planet