A kids’ film about Brexit might sound like a tooth-grinding ordeal, but British writer-director Joe Cornish’s second feature breezily combines political allegory with Arthurian legend. Eminently bulliable Year 7s Alex (Louis Ashbourne Serkis, son of Andy) and Bedders (the adorable, skittish Dean Chaumoo) embark on a quest to Cornwall’s Tintagel after Alex pulls Excalibur out of a scrap yard. Together, they must stop the evil Morgana (Rebecca Ferguson, having a blast and channelling the spirit of Theresa May) from transforming Britain into “a leaderless, divided land”. Merlin shows up to help; the younger, posher version is played by Angus Imrie, though a sneeze is capable of transforming him into both an owl and Patrick Stewart (in a Led Zeppelin concert T-shirt, no less).

I’m a huge fan of Cornish’s 2011 debut Attack the Block, but this film isn’t nearly as energetic or enjoyably wacky as its predecessor. In fairness, it’s pitched at a considerably younger audience, but at two hours it drags; less patient children may struggle. Scale-wise, the production feels a little like an extravagant episode of Doctor Who, though several of the film’s gags, however mild, might induce a chuckle or two, such as the teenage Merlin being sustained by ice-cream, Cherryade and chicken nuggets instead of beaver urine, beetle blood and ground bones.