Although this sitcom has never quite managed to be as good as the sum of its parts, it's been easy enough to watch.

And in the last episode tonight, it's a mini Smack The Pony reunion as we finally meet Tom's ex-wife, who is played by one of Sarah Alexander's former cast mates, Doon Mackichan.

Not only does the former Mrs Tom Marshall have an ability to get up people's noses (a bit like her annoying daughter), she also turns out to have the skills of a cat burglar as she manages to enter a house without actually being let in.

But before all that, Gemma (Alexander) has to cope with another unwelcome house guest - ex-husband Jason (Neil Morrissey), who has been kipping on her sofa since splitting up with Inca.

While assisting Jason with his love life, Gemma herself is still emotionally torn between soppy Tom (Nathaniel Parker) and toyboy Billy (Robert Sheehan) and as this is the final episode of the series, we should finally find out who she's going to choose.

Will she follow her head or her heart? Go for the yurt or the Scotch egg? Don't worry, that last sentence will make sense.

The bland but warm sitcom limps to the end of the series, with Gemma throwing a barbecue to try to get her berk of an ex-husband back together with his girlfriend. She's held hostage in domestic chaos and tortured by unfunny gags about not wiping down worktops but, more importantly, Gemma is facing a choice between the two men in her life: Tom's booking a mini-break in a yurt while toyboy Billy lurks in the background. With a trampoline set up next to the barbecue and a marriage proposal in the offing, what could possibly go wrong?

BBC1 sitcom behind BBC2's 'Natural World' in ratings

BBC One's Friday night sitcom Me and Mrs Jones is still struggling to pick up viewers, the latest overnight data for November 9 suggests.

Sarah Alexander interview

Me and Mrs Jones star Sarah Alexander talks 'seminal' show Smack the Pony and jumping into bed with 24-year-olds.

Sarah Alexander has revealed the hardest thing about playing a modern-day Mrs Robinson - snogging younger men. Despite the difficulties of locking lips with less mature actors, the former Coupling star is happy to play the older woman in BBC1 comedy show Me And Mrs Jones.

Sarah, 41, said: "In terms of getting older and moving on to the next stage, I am embracing it. I'm so thrilled to be a central lead in a comedy, particularly for BBC1."

But Sarah - playing Mrs Jones alongside on-screen ex-hubby Neil Morrissey and love interest Nathaniel Parker - confessed she was nervous about shooting steamy scenes with Misfits star Robert Sheehan - who is just 24. She said: "You wonder what they're thinking. You're wondering whether they're dreading it. It's an odd situation to be in."

Sarah Alexander interview

Sarah Alexander is happy to play the older woman, she tells Gerard Gilbert.

Dippy Gemma's (Sarah Alexander) complicated private life continues to traumatise her in this family sitcom, as she swoons over teenager Billy (Robert Sheehan) - who's "like catnip to the ladies". Alfie, Gemma's son, has invited her to a party, causing his mother to worry that she's looking too "Boy George" in her get-up. Meanwhile Jason's (Neil Morrissey) sensuous Swedish girlfriend Inca - brimming with "angry sexuality" - is trying to cajole him into dance lessons.

If Me and Mrs Jones, this crummy yummy mummy sitcom doesn't in itself herald the end of the universe, it does make you question what 14bn years of cosmic existence has achieved.

After the desperate opener, the humane hope was that, contrary to the second law of thermodynamics, things could only get better. But the second episode proved that hope to be vainer than Simon Cowell.

Character may not always be destiny in real life, but it is in real comedy. And like far too many British comedies, Me and Mrs Jones, a school gate farce, has no characters. Instead it has "types": the hapless single mother, the neighbourhood busybody, the humourless Nordic sex bomb.

To watch Sarah Alexander as Mrs Jones work herself into a mirthless fluster is to long to see Wendy Craig in a rerun of Carla Lane's 70s sitcom Butterflies, a yearning I have never previously felt in danger of experiencing. Yet say what you will about Craig's Ria, she was drawn from an active imagination rather than an exhausted comic trope.

The stock ciphers in Me and Mrs Jones possess no animating truth and therefore inspire no sympathy - the paradox of comedy being that you have to feel for people before you can laugh at them. Whatever pity was mustered went on the actors, whose lines were so limp that it seemed like a cruel and unusual punishment to leave them dangling without the protection of a laughter track.

In historical terms, the demise of the laughter track must be hailed as a positive development in British sitcom. For is there not something creepily controlling about being prompted to laugh? Apart from anything else, it denies us the basic human right of spontaneity.

But with the sort of sitcoms that British television churns out with mystifying regularity, the laughter track performs a vital practical role. It provides the only sign that these shows are comedies. Take that away and you're left with an extreme version of Brechtian alienation, only without the intellectual kudos.

When, for example, Inca the Nordic sex bomb said: "I am Swedish", you could detect immediately afterwards a ghostly appeal to a notional sense of humour - the empty beat where the laughter was supposed to go. Call it the silence of comic entropy, this was the haunted sound of a joke that had not just died but decomposed into absolute nothingness.

Now that the situation has been set up, the comedy gets more elbow room - and while the eponymous Mrs Jones is undeniably scatty and has all the social graces of a love-struck teen, it's the men who end up looking foolish.

Gemma's clueless ex is in thrall to waxing fiend Inca, while her date with Tom makes him behave like an eager puppy, and son Alfie's attempts to seduce "one of the cashmere pashmina-wearing Nigellas" at school are downright embarrassing. The only male to escape with any credibility is the lovely Billy (Robert Sheehan).