The mussed-up style can feel uncertain, but there’s a sincerity to Sharpe’s treatment of Wain, in all his life’s shambolic aspects, that tugs away at you. Toby Jones, who plays Sir William Ingram, clubbable editor of the Illustrated London News, is such a trusty scene player you relax in his company almost on sight. As Louis’s unstable sister Caroline, Andrea Riseborough charges about at the end of her tether, a figure of flummoxed cartoon fury we never really get to know.

There’s a straightforwardly lovely Claire Foy performance as the governess, Emily Richardson, who was diagnosed with inoperable breast cancer after she and Wain married. Emily’s bright, practical manner of treating Louis more like a ward than a husband gives Foy her chance to shine: the film really loses a lot when she exits. But then, so does Louis, adrift in his private pain, with a growing army of cats as his main companions.

I’m not sure acting under mounting layers of ageing make-up is Cumberbatch’s best friend, any more than it’s any actor’s: over time, we come to feel unhelpfully distanced from the character and the performance. The intended poignancy of Wain’s decline is only there in theory.

Still, the film’s funniest touches – subtitled dialogue for cat noises – are a daft delight when it needs one. There might have been a weirder, wilder approach, with the cats themselves (“silly and alone, like us”, as Emily remarks) given more than bit parts. Imagine Terry Gilliam getting his paws on the inner life of Wain and going for broke. 

One trippy, kaleidoscopic interlude heads in that direction, suggesting something between a Doctor Strange wigout and 2001: A Cat Odyssey. But the distinctive charms of Wain’s aesthetic certainly come over, especially daubed across the lovely end credits, by which time this jumpy curio, with almost palpable relief, has laid itself to rest.

In cinemas from New Year’s Day