If Lucy Gannon were a horse, the bookies would be out of business. Not content with runaway successes in both the primetime TV series - Soldier, Soldier, Peak Practice, Bramwell and Hope and Glory - and the one-off TV drama, including Big Cats and Tender Loving Care, she now takes on the four-part TV drama serial in Pure Wickedness, a tale of small-town folk set in the Derbyshire peak district, clean country air and, ah yes, illicit sex. Given its inherently clandestine nature, precise statistics are impossible, but adultery is probably the most popular extra-curricular activity there has ever been, with the majority of husbands admitting to playing away and only slightly fewer wives - more than can be said for, say, pot-holing or hanggliding. However as Pure Wickedness makes clear, it is more dangerous than either. The territory Gannon explores is very similar to that of Tender Loving Care: ordinary people with ordinary lives whose only real desire is not to hurt the ones they love, which, of course, is exactly what they do. Unlike The Lakes, its cousin several times removed, Pure Wickedness sees no reason to expand the basics involved in marital infidelity: no murder, no incest, no multiple couplings, no wayward priests, just the good old eternal triangle. In the boring corner we have Kevin Whately, playing the cuckolded GP Dr Geoff Meadows, described by a colleague as one of life's cheerful martyrs. In the bored corner we have Orla Brady as the lissom Jenny Meadows, free spirit manque.
In the up-for-it corner we have Frank, the chancer to end all chancers. "It's men like you," says the already-weak-at-the-knees Mrs Meadows, "that give men like you a bad name." But bad isn't boring, neither for Mrs Meadows or this female viewer, at least, as Frank is played by David Morrissey, last seen as the equally up-for-it Kiffer, Jacqueline du Pre's errant brother-in-law in Hilary and Jackie, and walking proof that men don't have to be handsome and lean to be sexy. When it comes to gossip, a good tale of adultery is hard to match, whether it involves William Jefferson Clinton or Mrs Until-NowBlameless Neighbour. Indeed Mrs (or Mr) Until-Now-Blameless Neighbour, as Lucy Gannon knows, is the most interesting affair of all, through its there-but-for-the-grace-of-God proximity.
It's a different matter, of course, when it's closer to home: a best friend duped and dumped; witnessing an unsuspected infidelity and not knowing what to do about it; or worst of all, finding yourself "the last to know". Or is that the worst? Those of us who have never strayed might not experience the passion, perhaps, but neither do we experience the pain of being responsible for so much damage. Lucy Gannon is now on her second marriage and knows from first-hand the devastation the break-up of a family can cause. The honesty of her writing succeeds in pulling us right in to the core. She doesn't offer easy stereotypes: Dr Meadows isn't a boorish bastard, Jenny Meadows isn't a self-obsessed nymphet, Frank isn't a feckless father. And Frank's wife Mo (Lesley Dunlop) isn't a nag - although she has let herself go in the looks department. Nor are the circumstances exceptional - a chance meeting, a flirtatious remark, a brush of the hand - things that could happen to anyone, and do every day.
Adultery is, perhaps, the ultimate spectator sport. You may not get the adrenaline rush of the participants, but your place on the emotional rollercoaster is secure. And as for torrid sex, Orla Brady's hand on David Morrissey's fully-clothed back as he washes his hands at the kitchen sink is as erotic as anything I have ever seen on television. But for those with more traditional tastes in titillation there are nipples (female and male) and bottoms galore, though Kevin Whateley's is not one I would personally recommend - and indeed is enough of itself, I suggest, to mitigate his screen-wife's behaviour. Who would have thought something so naked could be such a turn-off?
Pure Wickedness begins on BBC 1 on Tuesday at 9.30 p.m.