That's a little too much information for me, thank you

Omigod! The Prime Minister has sex! With his wife! What a weird concept for a politician, says CORA MANN

Hurrah for the heart-warming news that Tony Blair has managed to find enough time amidst running the country to get Cherie with child (again). But at the same time it's a slightly disconcerting prospect that stretches the imagination just a little too far. It's akin to being at school and discovering that one of your teachers is pregnant and thus presumably must have had sex at some point fairly recently. The Blairs have always been a touchy-feely, hand-holding kind of couple, which is of course very nice, but since Friday there has been almost too much speculation about the exact details surrounding this happy event.

Cherie is 13-weeks pregnant, so when was the actual conception? Could it have been a pasta-fuelled romp in Tuscany, during what has been referred to as their "relaxing" (wink wink) holiday earlier this year? Could it even have been in Bournemouth during the Party conference, spurred on by the invigorating ozone-rich sea breezes? Could the deed have been done in France (so romantique)? Or even, erm, Downing Street? Apparently the pregnancy is a "surprise" so we can assume they still have recreational rather than procreational frolics! It has also been noted that in July, when Mr Blair was interviewed on BBC1's Newsround programme, he said "We would have had five if, well, if we had carried on, I suppose." They have certainly carried on doing something, fnarr! This is all rather more information than a delicate constitution wishes to take on board.

Blair's latest babe (ho ho) will be the first to be born to a prime minister in office since 18-something-or-other, and frankly this comes as no surprise. It's hard to imagine that Margaret and Denis or John and Norma could ever have delighted us in this way - hard indeed to imagine that Downing Street saw much sub-duvet action at all during previous terms of office. Prime ministers (in this country at least) don't shag. They drink whisky and write memoirs and fight with their cabinets.

But in other countries, knowing more than one might wish about the sex life of the leader of the nation is widespread. We might as well all have been there in the Oval Office with President Clinton and Monica Lewinsky and the cigar and the frock etc etc. While in France it's an open secret that male politicians have always been keener on extra-marital liaisons than on nappies and bottles and the patter of petits pieds. Parisian gossips have been discreetly murmuring for years about the French president, Jacques Chirac. It is rumoured that, on the night that Princess Diana died in a Paris car crash, no one could locate the elusive premier. According to a new book on the French political elite, there was no trace of Chirac at the Elysee Palace when the household was roused in the early hours of the morning. Mr Chirac's wife Bernadette was alleged to have replied, somewhat tartly, "You think I know where my husband is?"

One of late president Mitterrand's mistresses was rumoured to have been Edith Cresson, who he disastrously and briefly installed as prime minister, and one political commentator estimated that he had around 40 mistresses during his life, perhaps more. And the Blairs are a model of wholesomeness and restraint compared to the German chancellor Gerhard Schroder and his wife - or rather, wives. His fourth, Doris, is 20 years his junior. Doris is a political journalist and the two began a flirtatious and scandalous affair before Schroder eventually fessed up to his third wife, environmental campaigner Hiltrud Hampel. The subsequent acrimonious divorce amused the whole country (he accused her of interrupting cabinet meetings to deliver lectures on the rights of bats and said she wouldn't let him have his favourite sausages because she is a vegetarian). In last year's German general election campaign his rivals distributed T-shirts reading "Three Women Can't Be Wrong". The British can hold their heads high, secure in the confidence there won't be any such sleazy slogans flying around the next time we go to the polls.

Perhaps we should set squeamishness aside and try to feel proud that our potent PM, by not only staying happily married to his legal wedded wife but also by siring a fourth child with her, is setting a new precedent among world leaders. Maybe Tony and Cherie will usher in a new era of happy families in palaces, mansions and official residences the world over. So hurrah again, then, for the blissful Blairs - still having sex and still having it with each other.