Guuh ouh aah guah aaah. When I try to write how I felt while I was watching this episode, I end up doing little more than than transcribing my gurgles of pleasure. It’s the best episode since Listen. In fact, though Listen blew my socks off, this I enjoyed this more for quite simply distilling the very best of Doctor Who in general, and all the goodness of the Capaldi era (can we call it an era yet?) into 46 minutes of near perfection.

Boiling down the various different settings of Who – Earth historic, space futuristic, plus steam-punk space train – then adding in the classic monster mystery – borrowing from stories such Pyramids of Mars, Voyage of the Damned and The Unicorn and the Wasp – all this would seem to suggest a lack of new ideas… a sort of Who-by-numbers. Yet despite these many nods, this is a masterpiece in its own right. It’s so beautifully written and shot. And as well as combining these elements of classic Who so expertly, it also distils the most interest aspects of the new Doctor’s lack of empathy and the fragility of his relationship with Clara. Capaldi is at his absolute best, tiptoeing around Clara up to the point where he is working flat out to solve the mystery – and then, the pretence vanishes, and just as he did in Into the Dalek or Robot of Sherwood he does whatever needs to be done – even if it means Clara lying for him.

Best of all, the Doctor defeats (or, rather, solves) the mummy with one amazingly selfless act – and in 66 seconds does what no-one else in the room could have done. He’s heroic in his bravery and his brilliance – reminding us that if he’s been a bit inadvertently cruel lately, he’s still certainly not cowardly.

I love what this story doesn’t do, too – there’s no Missy/afterlife intrusion to cheapen the chilling deaths we witness (though I’d be surprised if the mummy-tech doesn’t prove to be connected with the afterlife when it is revealed). No polka-dot shirts with the magician’s outfit (in fact, Capaldi is dressed splendidly).

Terrific guest performances – particularly Frank Skinner (who so recently appeared in the Eighth Doctor story Dark Eyes 2) and David Bamber.

I think the only element that concerned me was Clara’s capitulation at the end of the episode. The Doctor was honest throughout, but he has not changed; Clara is obviously acutely conscious of what she would be giving up – but since nothing is resolved, I fear this storyline is going to rear its head again, while for me it feels like it has run its course.

But an absolutely terrific episode – and Jamie Mathieson has never written for the show before. They should get him back for another episode as soon as possible… (Don’t stop him now…)