Streatham style comes to Avenue George V. Marion Hume on John Galliano's ascension

At 3pm sharp on Tuesday, hundreds of faxes were simultaneously transmitted worldwide by France Telecom. They carried the announcement that John Galliano, the 35-year-old son of a Streatham plumber, was to succeed Hubert de Givenchy, 68, as the new designer at the haute couture House of Givenchy.

The announcement had been eagerly awaited. The identity of Givenchy's successor had been hotly debated until just after Givenchy's last haute couture show on Tuesday morning, marking the end of his 43 years as a designer. The rapturously received finale to a distinguished career ended with Hubert de Givenchy leading his teary-eyed workforce on to the catwalk to a thunderous ovation.

Fashion's international bush telegraph buzzes with gossip day and night. But the succession at the House of Givenchy was not one of the fashion world's usual open secrets. The combined silence of John Galliano, Hubert de Givenchy (who told me he did not know who his successor was to be) and Bernard Arnault, whose LVMH luxury conglomerate includes the House of Givenchy in its portfolio of businesses, meant that the secret - almost - remained safe until the news was official. Despite endless speculation, most of the international fashion pack did not know who had signed the contract to garner the most prestigious designer-for-hire job since the Italian, Gianfranco Ferre signed up with Dior in 1990.

The day before the announcement the names still being bandied about included Italy's mighty Giorgio Armani and France's cheeky Jean Paul Gaultier. But those with well-placed spies in Paris's tight fashion circles knew otherwise. Three weeks ago last Saturday, John Galliano was seen on Avenue George V, a smart Parisian street, a long cab ride from his cramped studio, which is virtually deserted on a summer weekend. The tall, elegant building at No 3 bears the name "Givenchy" in 12in-high gilt letters right across its honey-coloured stone frontage.

"There's this brilliant archive out at the back," Galliano at last admitted to me on Tuesday, when he was free to own up to his $200,000-plus (more than pounds 129,000) a season new job. He has already spent hours researching the sketches and toiles (three-dimensional patterns made in cloth) that record the life's work of Hubert de Givenchy. "I wanted to feel the spirit, to get the background," he added, although he insisted that his first haute couture collection - to be revealed in January - would not be a slavish reissue of Le Grand Hubert's best work.

Galliano was determined to maintain his silence until Hubert de Givenchy had enjoyed his swan song. Reached last Saturday at his studio on a boiling hot Paris afternoon, he insisted that he was there only to catch up with work on his eponymous ready-to-wear collection. That will be shown, as scheduled, in October. Creating evening dresses for the celebrations surrounding "the Miller wedding" (the marriage in London on 1 July of the American heiress Marie-Chantal Miller to Crown Prince Pavlos of Greece had, he said, put him behind with his already intense work schedule.

By Tuesday night, Galliano's major emotion was not fear at the huge task ahead, but relief that at last he could be honest with those who have been pestering him for weeks. "Only five of us knew: myself, Steven [Robinson, Galliano's right-hand man], Amanda [aka Lady Harlech, who has been Galliano's highly original muse for a decade], Mesh [Chhibber, Galliano's press officer, whose politeness had surely been tested over the past weeks], and John Bult [chairman of Paine Webber International in New York and Galliano's business partner]. Even in private, we referred only to 'the G word', not daring to say Givenchy out loud."

What Bernard Arnault, who is now Galliano's boss, will be hoping is that the lad with dreadlocks and Errol Flynn moustache can do for the House of Givenchy what the man with the grey pigtail and fan, Karl Lagerfeld, has done for the House of Chanel. Lagerfeld, who has been the extremely highly paid hired man at Chanel since 1983, has kept the name constantly in the public domain thanks to exuberantly shocking collections that often must have had the chic Mademoiselle Chanel turning in her grave. The big difference for John Galliano is that Hubert de Givenchy is still alive.

Not that the south London lad who once provided models with wet mackerel to hurl into the audience at one of his London shows is expected to set out to shock Monsieur de Givenchy, who will be invited to the January 1996 show. Instead, those of us who have followed a roller-coaster career since the "Incroyables" college graduation that launched Galliano 11 years ago are hoping to be thrilled. We won't be expecting to see Galliano "do" Givenchy; instead, with the back-up of some of the best technicians, tailors, seamstresses and crafts people in the fashion world, plus significant funds, we will be expecting to be enchanted with something modern and new. John Galliano has yet to secure a breathing space to work out what that might be.

The only thing that is probably safe to predict is that one of Galliano's all-time favourite models, Naomi Campbell, will turn up. The most famous young black woman on earth, aka the Streatham stray cat, and the hottest designer in the fashion firmament come from within streets of each other. Perhaps Mr Galliano Snr put something in the water?