Me and Mrs Jones opens with a goldfish in a toilet bowl. I can only guess that the goldfish took one look at the script and attempted to escape before his television career suffered irreparable damage.

Of the many unkind epithets suggested by Roget’s Thesaurus, excruciating is the one that best describes this show. Until I watched it, I did not realise it was physically possible to grit one’s teeth, curl one’s toes and clench one’s sphincter all at the same time. And stay that way for half an hour.

Purportedly a romantic comedy, it is about as light and fluffy as a breeze block. Not the most sparkling of analogies, I grant you, but better than anything the lazy and witless script of Me and Mrs Jones had to offer.

“Houdini would have trouble getting out of this dress,” grumbles our scatty, sexy heroine Gemma, as she writhes around in a store changing room. Houdini? The escapologist who died 88 years ago? Watch out for further thrillingly contemporary references to the general strike, Irish home rule, speakeasies and the disappearance of Amy Johnson.

Where the show strives to charm, it succeeds in irritating. I am a fan of Sarah Alexander, who plays Gemma, but here I found her wackiness so mannered as to be unbearable.

But the worst thing about Me and Mrs Jones is that no part of it rings true – not the characters, not the relationships and definitely not the dialogue. Romantic comedy needs to appear effortless, but every minute of this contrived, constipated monstrosity screams with the strain of it all.

A solidly dependable cast, including Nathaniel Parker and sitcom stalwart Neil Morrissey, tries so desperately hard to unearth humour from the barren comic landscape that I actually began to pity them. This is particularly true of Jonathan Bailey, lumbered with the Herculean and ultimately futile task of lending sympathy to Alfie, Mrs Jones’ unremittingly loathsome eldest son, just back from his gap year abroad. Apart from a big mouth, an overinflated ego and a penchant for harassing women on public transport, Alfie also has a best mate in tow, who just might hit it off with his mum over the next five episodes.

Andy Samberg (Cuckoo) and Greg Davies (Ken) in Cuckoo. Photo: Roughcut TV/BBC

Continuing the gap year theme, Cuckoo follows the comic misadventures of a staunchly middle-class family coming to terms with their daughter’s choice of husband – a New Age American airhead she met and married in Thailand.

Three episodes into the series, and Cuckoo is settling down nicely. The premise is exploited to the full, the scripts are consistently amusing, and the performances of Greg Davies, as the bumptious, blustering dad, and Andy Samberg, as the pseudo-spiritualist slacker son-in-law, complement each other perfectly. Plus, any show featuring Helen Baxendale is a good thing by definition.

Mr Bates, former footman at Downton Abbey, is still languishing in a cell, serving life for killing his wife. Given the time, effort and expense of recreating an entire early 20th-century prison just to accommodate this one tangential plotline, what’s the betting the producers now wish they’d had him hanged at the end of series two?

Me and Mrs Jones, BBC1, Friday, October 12, 9.30pm
Cuckoo, BBC3, Tuesday, October 9, 10pm
Downton Abbey, ITV1, Sunday, October 7, 9pm