Because Man O Man, Tarrant's addictive Darwinist hen party, which made a welcome return last night after a brief football-inspired hiatus, is a landmark in Saturday night entertainment and a legend in the making, and we need to know how it happened. "I'd seen it. Where did I see it first? It was in Germany about three years ago. There was this barful of demented drunken German ladies screaming abuse at a load of scantily clad men who kept getting pushed into swimming pools, and I thought 'that's a very strange piece of entertainment'. So when I'd been chewing the fat about various programme ideas with Grundy TV [purveyors of Man O Man, also responsible for Neighbours and Crossroads], they gave me a tape and I put it on and thought 'oh it's that one. Are we sure about this?' "
How could he possibly have had any doubts about a show wherein a group of 10 men are gradually whittled down to a single winner by being obliged to sing, dance, tell jokes, do absurd physical exercises and answer extremely pointed questions to the satisfaction of a rabid assemblage of 300 drunken women? "You knew that inevitably there would be a load of flak and a lot of people saying 'this is the lowest that TV has ever sunk'. I went to lots of meetings before I signed on the dotted line, because I really did want to keep the 6.30-7pm family audience. I saw the Norwegian version, and bear in mind I'm married to a Norwegian [Ingrid, the second Mrs Tarrant, lives in Surrey with Chris, who is 49, their two young children and two older children from her previous marriage; Chris's two other children from a previous marriage are grown-up] and it was absolute filth."
There's something very wholesome about the British version though, isn't there? A natural quality that's a far cry from the over-scripted salacity of Blind Date. "I keep reading all this stuff in the broadsheets about the contestants being humiliated and I just think 'oh please'. The men are quite dignified aren't they?" Tarrant laughs: "I don't think they're particularly dignified, but you certainly don't sit there as a guy thinking 'this is ridiculing my sex'."
That this should not be the case is at least partly down to the tact and discretion with which Tarrant ("I'm their only hope, I really am") handles the job of defending the interests of the beleaguered contestants. These are not qualities for which Tarrant is often celebrated, but ever since the Saturday morning mayhem of Tiswas, crowd control has always been one of his specialities. Are the audience as drunk as they look? "They only get 45 minutes in hospitality with some fairly grisly old sangria, but what we didn't anticipate was that they've all had 17 gin and tonics in the pub before. They do this thing with the keypads for some reason, as if, if they hit them hard enough, the man they're voting to get rid of will go in [to the pool] deeper and faster."
It would take years of psychoanalytical training to comprehend fully the Freudian implications of this process, but the gladiatorial element in Man O Man is clear to the layman. "It's Caligula all over again." Tarrant makes a cheery thumbs-down gesture. "The poor guy has only been on TV for five seconds and said 'hi girls, I hope you like me', and they're screaming 'die, you smarmy git'."
It's nice for the male of the species to have a ritualised arena in which to put his manhood to the test without hurting anybody, and it seems very appropriate that the winner should get a motorbike. "The men are all pretty twitchy, as you can imagine, and we don't let them drink all day, but after they've been in the pool they dry themselves off and they're in the bar like scalded bunnies. There's a tremendous camaraderie there."
If only all those sad men who go on Iron John weekends, hunting bears in the woods and living on acorns and twigs, could be encouraged to take part in Man O Man, the benefits for contemporary masculinity could be incalculable.
What is particularly heartening for the non-Brad Pitts of the world is that the conventionally attractive man seems to get very short shrift. "When a really good-looking guy comes on, at the beginning they're all going 'ooh look at him, he's strong and he's got trim little buttocks', then you suddenly notice the mood change, it's very odd. They turn, as one terrifying single woman. Basically it's revenge for all the good-looking guys in the world who have treated women like dirt for years. There was one show where this guy looked like something out of Baywatch - you wanted to dislike him but actually he was just a really nice guy - and he played a good electric guitar, and I thought 'this is a bit of a romp tonight, it's a bit of a waste of time for the other guys'. But then he played that guitar and they sort of went 'hmmm', then they did the question round and they absolutely hung him out to dry. The next thing he knew he was in the pool."
Does he think there is anything to be learnt from Man O Man? "Basically that men and women should stay completely apart; there's no point even pretending that we like each other." But surely this show is going to bring about a huge increase in understanding between the sexes? Tarrant shakes his head earnestly. "Every time I leave the studio, the gap is wider. I'm thinking, 'what was it about him that they didn't like?' They're screaming 'he's got to go in'. Ask them why and they just say 'the shirt'."
At this point, Tarrant dons his souvenir Auberon-Waugh-voice-of-endangered- masculinity codpiece. "All that stuff about 'at long last women get their own back'. Okay that's true, but this 'at long last' thing - women have actually been getting their own back all my life." He basks in the surprised silence. If Tarrant actually believes this, his personal career parabola must stand as an object lesson in how to dodge the depredations of a stern and vengeful sisterhood.
The Tarrant gene pool was awash with get up and go. Chris's dad worked his way up from teaboy to a seat on the board in a Reading-based biscuit tin empire, but his own early career progression was haphazard. Chris meandered from long-distance lorry driving to education, sleeping in a mini van outside the tough New Cross school where he taught. "I drove through there in my big fat Merc the other day. If you see the road now, you can't believe anyone would leave a car there with a human being in it and both the car and the human being would still be there in the morning."
He made films for the Central Office of Information (a 12-second black-and-white epic about Britain's longest rope won a prize in Romania) and then, legend has it, applied for a job at every television company in Britain. Did he really describe himself in his begging letter as "The Face of The Seventies"?
"I think I probably did." Was he thinking of posterity at that point? Tarrant guffaws: "I think in 1996 I probably am the face of the Seventies."
How does it feel to have been on the more robust side of one of British youth's great formative dichotomies, Tiswas/Swap Shop - ranking as it does with Oasis/Blur, E17/Take That and Magpie/Blue Peter? "They used to say 'you've got to be careful, one of the kids might start crying' and I'd say 'well, if you go to kids' parties, sometimes the children do cry'. But they never cry on Swap Shop, and you'd think 'no, and that's why it's so boring ... and anyway, Keith Chegwin always used to look quite close to tears."
Man O Man continues on ITV next Saturday.