The French publisher Parigramme recently brought out a handy little pocket- sized volume on the best places to kiss in Paris - restaurants, boulevards, salons, jardins, boutiques, the lot (for more details, see right). But Paris is one of the world's most famously romantic cities. Wouldn't a guide be more use in London, where romance is rather lower on the list of reasons to visit? Dr Peter Collett of Oxford University, author of Foreign Bodies, a study of European mannerisms, would agree. "We're not a kissing nation. In this country there are no rules on where you kiss, which side, how many times, and that's the measure of a kissing country - though it's important to remember that social kissing and romantic kissing are two quite separate things."
Where would he suggest in London for a revival of such practices? "That lovely high-up spot on Hampstead Heath where people fly their kites. Or a fleeting moment on an escalator on the move."
But an uninhibited display of mouth-to-mouth affection is not always considered quite correct. In this month's Tatler magazine, the columnist Cressida Connolly tuts over the whole issue of public displays of passion. "Connubial bliss used to be a private matter; hugging and kissing went on behind closed doors," she harumphs. "Couples should only touch in public when their fingers brush as they pass the car-keys. Anything else is too much."
Drusilla Beyfus, doyenne of etiquette and author of Modern Manners (Mandarin pounds 6.99), is less draconian. "I think a book on kissing in London would do very well indeed. Now London is such a centre for tourism, I'm sure they would all love to be told that they should kiss under Nelson's Column but not in Westminster Abbey." Public kissing is fine, she says - up to a point. "In this country, when we're not maintaining a stiff upper lip, we tend to go into a full clinch, which is embarrassing. Kissing is OK as long as it's done in a restrained way. What underpins good manners is the principle that you should never embarrass others or make them look away, so passionate kisses are out - they should be light, tender, affectionate. If you happen to catch a Frenchman kissing his wife out of the corner of your eye, it's a gesture that's full of tenderness but not embarrassing to notice."
And where might one go? "London parks in springtime are jolly good fun - the little temples in Kensington Gardens, or feeding the ducks in Hyde Park," suggests Ms Beyfus. "Or Waterloo Bridge, a very romantic spot."
The London Tourist Board (0891 505440) is indignant at the very idea that London is less of a kissers' paradise than Paris. "We have never understood why there is this notion that Paris has all the romance," says spokeswoman Louise Wood. So where is the LTB lovers' guide to London? "Erm, well, we don't have any specific publications. But we've got lots of ideas." The tourist board would pack kissers off to the Dulwich Picture Gallery; the flirtatious Fan Museum in Greenwich; the Peace Pagoda in Battersea Park with its beautiful view over the Thames; or Floris, the old-fashioned perfumery in Jermyn Street SW1. The staff nominate Little Venice on the Regent Canal in Maida Vale as the "prettiest and most romantic spot in town".
Though really, if you are not too much of a shrinking violet, you can kiss pretty well anywhere. "I think the only thing some people are still up-tight about is gay kissing," says the poet Fiona Pitt-Kethley. "Kissing in public has been OK for years - well, I've certainly done it for years. In fact, I've done a lot more than kissing in public, and it doesn't bother me at all."