Patrick Mulkhern has previewed “The Doctor, The Widow and the Wardrobe” for the Radio Times, teasing some of the things that will happen throughout the festive special, so if you’re completely avoiding spoilers then stop reading now!

It begins spectacularly with a gigantic spaceship looming over Earth, in what has to be a homage to The Hitchhikers’ Guide to the Galaxy. But the drama really centres round the Arwell family, a widow and two children, who have been evacuated to an imposing house in the English countryside in 1941.

Here the Doctor, travelling alone, just happens to be caretaker. Matt Smith is as usual utterly beguiling, and funny, while Claire Skinner is heartbreaking as the resilient Madge, a world away from the frazzled mum she plays in Outnumbered.

There are nods to Narnia: the episode title, obviously, and a portal that leads from the house into a snowy forest, but here the allusions end. CS Lewis won’t be revolving in his grave. The wartime stiff upper lip and cosy period detail lend a terribly British glow, while the trappings of Christmas – prezzies, trees, baubles – are imbued with a sense of menace and magic.

The guest monsters, brilliantly realised, are made of wood. Bill Bailey, Arabella Weir and Benidorm’s Paul Bazely provide gentle comic relief as incompetent harvesters. (Die-hards should listen out for a reference to a 1984 story.) And Maurice Cole and Holly Earl play the Arwell children, Cyril and Lily, with great conviction. Where do they find these young actors?

I’m not letting anything else slip, apart from a few lines of dialogue: “I got dressed in a hurry”, “Why does a forest need people?” and “Happy crying…”