"Are you my mummy?"
Yes, they couldn't resist it.
No blitz-dodging, gasmark-wearing nippers this time though, just a rancid old vet that even a decent vet couldn't save.
For he is the Mummy on the Orient Express who, despite his state-of-the-art soldiering kit is not really what the passengers had in mind when they were promised "all mod cons".
The Doctor plays Poirot, Clara looks in need of a Charleston and Perkins bears an uncanny resemblance to "that disc jockey" (but thankfully not the white-haired Hartnell-alike).
Jelly babies are shared, old ladies fulfill their job descriptions and the kitchen staff are let outside for a breath of fresh vacuum.
But is it a rattling good locomotive of an episode? Or derailed stock which refuses to roll?
Jim and Martin take rather more than 66 seconds to decide.