Literary critics talk of the inexorability of tragedy, the inevitability by which the hero is felled by his tragic flaw. Less is said of the inexorable grind of comedy, of how the dolt will unerringly be brought down by the banana skin. Naturally, this is not true of all humour. Spoken jokes, for example, rely on unexpected punchlines. But it is true of farce, and because of its predictability, farce has to work doubly hard to be funny rather than wearisome. Plots need to be oiled, double-takes perfected, editing slicker than slick. People look down on it, but good farce catches you helplessly in its mechanism and there is no more an escape from its hilarity than from its stupidity.
At its best, The Worst Week of My Life (Fridays, 9pm) is a farce. We should excuse its predictability and praise its execution therefore. The premise of Mark Bussell and Justin Sbresni's sitcom is that the happiest day of your life, your wedding day, is often preceded by a week of fear, tension and mishap. No one could accuse them of straying into original territory. What can go wrong will, you can be sure, go wrong: from the wedding frock to the wedding breakfast, from the sulky bridesmaid to the jealous ex-girlfriend, from the bride's in-laws to the groom's.
As soon as we hear in the opening episode that Howard Steel has arranged the alterations to the expensive wedding ring, we know it is going to be 50/50 if it ever makes it on to Mel's finger. In this case, Howard's unprepossessing spinster secretary gets it stuck on her finger. When, finally, her colleagues pull it off in the loo, it slips down a plughole. The director, Dan Zeff, acknowledges the fateful inevitability of all this by filming the flying ring's aerial trajectory in slow motion. We follow it as it spins around the basin like the ball in a roulette wheel and makes its final descent. It ends up in the sewer, where the comedy has been heading with equal inevitability. Zeff again raises the tone a little by shooting this in gentle imitation of Lord of the Rings.
The laughter is so predicated on what we fear will happen actually happening, that when the set-up does not produce the expected joke we feel a pang of disappointment. Mel's mother is a terrible cook and Howard is allergic in particular to her goulash. He secretes what he cannot eat in his pocket, just as we have seen gormless heroes do since comedy (or pockets) began. Enter sniffing, hungry dog. But the dog, although interested, does not go for the kill and Howard's jacket pocket survives, as do the chunks of lamb - but only so that they can surface in a much better gag a little later when he tries to flush them down the lavatory and they prove unsinkable. Howard's about-to-be father-in-law enters by accident and finds Howard, to all intents, handling his own stools.
When inspiration like this hits, Worst Week is just as good as the Ben Stiller/ Robert De Niro comedy Meet the Parents of a few years ago. Far more care has been taken with it than with most British sitcoms and it earns its right to play without a laughter track (there has been a vogue for this self-sacrifice since The Office, but it does no service to your standard unfunny fare). Ben Miller is his near-namesake's equal as the terrified groom heading for the slaughter, and if Geoffrey Whitehead as his father-in-law (a judge) is not psychotic like De Niro was, he is lethally cold, determinedly building a wall in his garden as if to thwart the coming alien invasion. When Howard asks if he has "sent anyone down today", he replies with deliberate obtuseness: "What do you mean?" He sounds as if he has just sentenced Howard.
What this British sitcom has that the Hollywood film did not is class consciousness. It is not overplayed - rather treated as just another obstacle, like the lamb goulash - but it is there. Howard is marrying above himself. His fiancee's family lives in a big house with a big drive. His own widowed father, as we shall discover, lives in suburbia, if that, and has acquired a plebeian girlfriend - a lap dancer, in fact - whose coarseness shocks even Howard. On the other side of the social divide, Mel's unpleasant sister (Emma Pierson) is a particularly well-drawn portrait of Sloanish vulgarity. Only Alison Steadman, that diva of suburbia, seems less than perfectly cast as Howard's new mother-in-law. Playing Mel, Sarah Alexander looks as sweet as you like, but has been left with very little to do in the way of getting laughs: she is sensible, unsnobby, forgiving, occasionally exasperated. Bride as stooge.
The only unusual thing about this comedy is that it is rather funny. In no other way is it distinctive. One cannot compare it with Garth Marenghi's Darkplace, for example, which has just finished a wonderful run on Channel 4 and showed such verve and originality. But as mainstream, BBC1 comedy, it deserves to attract some attention and some praise. Meanwhile here's a poser. The second episode features that darn ring, that darn dog and a cement mixer. See if you can guess what goes into what, and in what order.
Andrew Billen is a staff writer on the Times