"The English are frightened of baby fragrance but the French love it," says Michelle Levy, manageress of the Knightsbridge branch of Jacadi, a French childrenswear company which sells a range of baby bath products as well as perfume. "You can't imagine putting fragrance on a baby. It sounds horrendous," she admits. "Some mothers look at it but just can't understand it. But once a mother buys it, she comes back for more. I think it will definitely catch on with British mums, eventually."
Henry's mother, who is browsing, does not agree. "Totally unnecessary," she snaps. Meanwhile, Henry holds out his wrist as he has seen his mother do in the perfumery at Harrods. He looks on curiously as some of the perfume, which comes in a child-friendly squidgy plastic bottle, is squirted on him. He tries to lick it, and smiles. "It smells nice, mummy," he says. Perhaps this is why mothers end up wearing the £6.50 fragrance themselves: their children like the smell.
Mrs Costes is pushing a pram round the baby-gro section. She is French. I ask her if she would like to try the Jacadi baby scent. "It's without alcohol?" she asks. It is. "No problem," she shrugs. The idea of baby perfume is perfectly natural to her.
Across the road from Jacadi, in the Harrods perfumery, the nice lady behind the Guerlain counter is cooing reassuringly: "It's very soft, very gentle." She is squirting Petit Guerlain on to the back of my hand, telling me that it is popular with the Japanese, and is good for people with allergies. It smells pleasant and lemony. "But isn't it for babies?" I ask. "Oh yes, but only the most sophisticated babies. It is a sophisticated perfume."
Baby fragrances are widely available on the Continent. Mrs Mason, mother of two, buys her children cologne called Nenuco from Spain each year and has used it on her children, James, two, and Sophie, seven, since they were born. In fact, the scent has been in the family since the birth of Mrs Mason's little sister in 1972. The attraction is the fresh, clean smell which friends and other parents often comment on. No matter how dirty a baby gets, it will at least smell clean with eau-de-Cologne.
In France, the idea of buying perfume for your baby is as normal as buying nappies. Anouk Morgan is half-French, half-English, and both she and her mother thought that all babies wore cologne. One of Anouk's earliest memories is of being splashed with a baby scent after her bath. "I was told it was to stop you growing mushrooms," she says.
Givenchy's Ptisenbon (which presumes Baby has a basic grasp of French pronunciation as well as a finely tuned nez) makes no promises about arresting fungal growth. Launched in Europe in 1987, it was developed instead to complement the fashion house's children's wear range, Tartine et Chocolat. Sold here since September, it comes in a range of products, just like mum's. There is eau-de-toilette, shampoo, soap and bath gel, all available in eau- de-senteur, which means it is alcohol-free, so no danger of burning Baby's skin. Perfect.
There is something very un-British about the use of perfume, unless it is Old Rose or lavender water. Givenchy sells twice as much adult perfume in France as it does in the UK. As Peter Norman, managing director of Givenchy Parfums in the UK, says: "Champagne is French, perfume is French; it is part of their heritage. We drink more malt whiskey." But as more and more children are introduced to it from an early age, we too could become a nation of perfume connoisseurs. Mr Norman is predictably confident: "People in this country are coming round to the idea of children's fragrances. I see no reason why it won't catch on on the same scale as in Spain, Italy and France."
Sounds suspiciously like a cynical attempt at attracting the perfume and aftershave buyers of the future, seducing young innocents into the beauty myth before they have time to catch their breath. And once they've outgrown their toddler smells, Givenchy, for one, is ready with a teen version, Fleur d'Interdit.
Jessie, three, and Fred, nearly six months, won't have this treat in store. Their mother, Barbara Downs, is horrified at the thought of spraying perfume on her children. "You can't beat their own smell, so why add to it? It would be like painting a lily."
Back at at the Givenchy counter a mother is saying that the aromatic, atmospheric Ptisenbon makes her want to have babies all over again. It surely won't be long before Calvin Klein launches CK For All The Family.