It’s fair to say that Roald Dahl’s 1980 children’s book The Twits offers a strong aversion to ‘bad’ people, and a general consensus that they’ll inevitably get their comeuppance. It’s not a particularly original idea but the story itself is a wickedly funny one and gets to the point in a short and snappy way. The stage adaptation just really, really does not.

Dahl’s book tells the story of Mr and Mrs Twit, a profoundly nasty couple who enjoy nothing more than playing rather unkind tricks on each other. They also intensely hate society. A lot. Oh, and monkeys. Enda Walsh’s adaptation has monkeys (Welsh ones) and a similar order of events (well, the beginning and end) but with other characters added in: three circus folk from Yorkshire. Walsh has aimed for a fleshier, more substantial and, I presume, more interesting piece. When the original source material could have proven more than sufficient, this results in the show feeling distinctly unnecessary.

John Tiffany has made The Twits lively and funny but the target audience is unclear. Marketed as being for ages eight plus, it’s a safe assumption that it’s mainly for children, with silly utterances like “eye bogey” generating a gleeful echo from a child in the audience, and the sequences between our vile protagonists that sees them play gross-out jokes on each other. Yet the tone ultimately feels mixed up and lacking in direction. There’s much black and disturbing hilarity as Mr Twit (Jason Watkins) often wields a shotgun, and much of the second act in particular plays out as a sketch show, but the jokes go completely over the young ones’ heads. There’s an overwhelming farcical style that for the most part is completely ridiculous and baffling. One scene sees Mrs Twit (Monica Dolan) and the circus folk break out into a rendition of ‘Grandma We Love You’ before the former switches into The Queen doing her Christmas speech and explaining her hatred for children. This is very, very funny but utterly surreal. Tiffany has tried to make The Twits edgy but this leaves the entire piece completely jumbled and without a clear style. The Twits’ initial appearance is alarming as they scream their names against a backdrop of rock music, and there’s other scenarios as well where characters suddenly go mental with some damning beats. It’s so obvious what Tiffany has tried to do, but the quirkiness unfortunately just doesn’t work.

However, Chloe Lamford’s set develops from The Twits’ gritty home, complete with a monkey-inhabited cage, to a more rounded and substantial feast as what can only be described as a drawbridge descends into the ground. It looks great and gives the cast plenty of room to manipulate. Aimee-Ffion Edwards’ Monkey Daughter leads a strong ‘family’ and both her and her brother (Oliver Llewellyn-Jenkins) give relaxed and comical performances. Dolan and Watkins do what it says on the tin. Theirs are strong inputs but unfortunately are not enough to gain any control over an overall weak show.

It’s a great shame because there are some very funny moments, but farces don’t always work and they’re generally always going to be a huge risk. The story and direction suffer from a severe lack of structure and would have benefitted from keeping closer to Dahl’s book.

The Twits is playing at the Royal Court theatre until 31 May. For more information and tickets, see the Royal Court website.