It’s not his fault, not really, but Richard Curtis has opened one hell of a can of worms with his ‘charming and risqué London-based romantic comedy’ thing – films like Notting Hill and Bridget Jones’ Diary are so effortlessly enjoyable that it’s easy to convince yourself you could do just as good a job yourself. Writer-director Jonathan Newman appears to have fallen prey to some variation of this condition, which has tragically resulted in the unspeakably dire Swinging with the Finkels. One can only hope that whatever he picks up next is more debilitating.

Alvin (Freeman) and Ellie (Moore) are worried. Their life together might seem comfortable – he’s an architect, she’s a fashion designer and they live in a cavernous South Bank apartment near a cheese shop – but after nine years together things have become distinctly stale. Everyone seems to have a different opinion on what will help matters; Alvin’s best mate Peter (Silverman) extols the virtues of pornography whilst his boss advises dressing up as a fireman, and Peter’s wife Janet (George) is too neurotic about losing her own looks and/or husband to be any use to Ellie. However, her eyebrow-pluckingly gay assistant Andrew (Edward Akrout) lets her in on his secret way of keeping things fresh with his partner (LOUIE SPENCE) – they indulge in regular partner swapping.

Alvin’s not sure he wants to get involved in swinging, but Ellie is insistent that nothing be off limits in the quest to save their marriage – and when Peter and Janet suddenly break up over Peter’s extra-marital indiscretions, everything’s brought very close to home. So, their respective misgivings aside, the Finkels wade into the distinctly cloudy and under-maintained swimming pool that is the London swinging scene. Will they find fresh enthusiasm for each other in a stranger’s arms? Will they remember to use multiple condoms? Will anyone explain to me why Louie Spence’s character is Spanish, given how irritating his voice is even when he isn’t affecting an accent? It’s like a murder mystery, except nobody’s dead and you wouldn’t care if they were.

There aren’t many rules to making a romantic comedy, other than that it should contain romance and comedy. Swinging with the Finkels boasts neither. What it does have in abundance are gratuitously crude and unfunny sight gags – like the scene above, in which Melissa George’s character arbitrarily milks herself before offering a beaker of her warm and freshly churned boobie-juice to Mandy Moore. The entire scene, which is never referenced or contextualised elsewhere, appears to have been included solely so the Swinging with the Finkels press release could include the matchless phrase “Peter’s lactating wife Janet…”. Elsewhere, characters have their cheeks daubed with mascara (it’s easier than actually doing sad acting) and make constant racist jokes about the one poor Indian chap – whatever you were paid, Paul Chowdhry, it wasn’t enough. Martin Freeman’s character is at least 75% composed of his trademark doleful look; the other 25% is made up of a series of dreadful outfits, which do at least distract the audience from the painful spectacle of watching a superb actor struggle manfully with the garbage he’s been told to say and do.

Mandy Moore is shatteringly insincere throughout, and the scene in which she violently rogers herself with a cucumber is up there with the most uncomfortable things I’ve ever witnessed. An entire portion of the film, the ‘interviews’ which Alvin and Ellie conduct with potential swinging partners, is constructed exclusively to introduce a feeble string of one-liners; this is possibly the second most irritating aspect of the film, after the asinine faux-aphorisms which appear typed on a black screen at random intervals. “One should always take relationship advice with a bag of salt”? It’s embarrassing, it genuinely is.

There’s not usually a lot of point in slinging hyperbole around, but I honestly think this is the worst soi-disant comedy film to be been produced in Britain for years. Combining a trite and one-dimensional plot with a spectacularly humourless script and a rash of unmemorable performances, the only genuinely intriguing thing about this excruciating cinematic clusterfuck is how any credible actors were persuaded to get involved in the first place. If any of you know Jonathan Newman, please tell him from us that he isn’t allowed to make another film – in fact, he isn’t allowed to do anything ever again, except sit in a very cold room and Think About What He Has Done.