This film contains flying children, time travel and a sand monster that lives under a beach — yet the most incredible thing of all is that a family get to go on holiday. They actually leave their house, drive down an actual motorway, rent an actual seaside cottage and go for actual walks, passing well within two metres of actual other people! And not once do Derbyshire police film them with a drone, then post intimidating footage of it on the internet.

The movie’s producers couldn’t have known they’d be releasing their creation into a locked-down world, but now that they have, who’s to say more people won’t watch it at home than would have watched it at the cinema? We are literally a captive audience. And there are certainly worse films to spend your time and money on. This is a perfectly serviceable — indeed at points rather charming — version of Jacqueline Wilson’s 2012 novel Four Children and It, which was itself inspired by E. Nesbit’s 1902 classic Five Children and It.

I say ‘a family’ go on holiday. The clever Modern Britain twist on Nesbit’s original story is that it’s two half-families — David (Matthew Goode) and his two children, plus his new American girlfriend Alice (Paula Patton) and her brace of kids. Needless to say the respective youngsters don’t get along. Until, that is, they stumble across the sand monster (the ‘Psammead’), who is small, grouchy and — thanks largely to the fact he’s voiced by Michael Caine — a bit of a star. He grants wishes (one per day, nothing longer than a sentence) by puffing himself up, then expelling all the air. Not the usual waving of a wand, but then, as he explains, ‘some of us have to work with enchanted stomach gases’.

The kids have some nice lines, such as: ‘When do the fashion police get here? You might still have time to run.’ Alice’s daughter Maudie (brilliantly played by Ellie-Mae Siame, who is all of five) explains why her father ran off with another woman: ‘She reeled him in with her tight 20-year-old tushie.’ While they’re off on their adventures, Alice stays at the cottage and has a series of cooking disasters. Though, as she’s having to work with an Aga, they’re not her fault.

Villain of the piece is Russell Brand, a local landowner who lives in a mansion and is meant to be eccentric. I say ‘meant to be’ because, although wardrobe and make-up have done their best (velvet smoking jackets, a beard halfway between those of Rylan Clark-Neal and Osama bin Laden), Brand himself employs an accent which — in as much as it stays in one place at all — is rather less mannered than the irritating one he employs in real life. This is the first time I’ve seen the entirety of a Brand acting performance (my luck had to run out in the end), and based on this evidence he really isn’t much cop.

The end credits contain a cameo from Jacqueline Wilson as herself, and also reveal that Cheryl, having been a Tweedy, then a Cole, then a Fernandez-Versini, has wisely decided to call herself just ‘Cheryl’. She plays the manager of a pop star that one of the children is turned into as their wish. At the moment the rest of us would probably settle for being allowed to buy an Easter egg.