For all his fruitiness, Callow is a convincingly regretful and magical Blunden. What this update has in abundance is charm, humour, sterling child casting and excellent comic-grotesque turns, particularly from Amanda Lawrence as a hunched-over servant.

Similarly – spoiler alert – whereas in the film, Blunden’s self-sacrifice is devastating, there isn’t quite the emotional connection here. Gatiss’s new version focuses far less on visceral creepiness, which is a shame: call me an old goth, but I like to feel spooked by spooks. Gatiss’s adaptation has big britches to fill: the 70s film, starring Laurence Naismith, is a cult supernatural classic (check out Diana Dors as a chilling Mrs Wickens). Blunden, their lawyer, ignored the children’s pleas for help: can this centuries-old wrong be righted? There’s a caricatured English love interest who barely stops short of doing the Lambeth walk While there, her children, Lucy and Jamie (Tsion Habte and Jason Rennie), meet two child spirits, Sara and Georgie (India Fowler and Xavier Wilkins) – not ghosts but time-travellers who perished 200 years ago in a fire set by the scheming Mr and Mrs Wickens (Gatiss and Tamsin Greig, the latter resembling a Crimewatch photofit of Nanny McPhee) in order to steal Sara and Georgie’s inheritance. In the present day, a widowed, impoverished mother (Vinette Robinson) becomes the caretaker of a mansion. While not about Christmas, it resonates with yuletide themes: love, redemption, ghost orphans in pantaloons and petticoats needing help, a gothic, vine-choked mansion, and Simon Callow, as Blunden, enunciating dialogue with such magnificent violence, it’s a festive miracle there weren’t reports of plasma screens shattering nationwide.

Based on Antonia Barber’s 1969 book The Ghosts, which was made into a 1972 film by Lionel “Railway Children ” Jeffries, The Amazing Mr Blunden is a ghost story set in the modern day and 1821, with Mark Gatiss as writer, co-star and director.

The Ghosts by Antonia Barber