He stood in the street looking up at the alarm with an expression on his face that might best be described as sheepish. To his dismay, the old guard of the Row took a disturbing interest in the volume of noise filling up their street.
The tailors gathered on their front-door steps in the lunchtime sunshine to see what the fuss was all about. 'Oh my God,' wailed James, 'they're going to hang, draw and quarter me.'
Bernard Weatherill, former Speaker of the House of Commons and president of his family's tailoring business, came out of his shop opposite and looked James up and down. It seemed highly unlikely that either man recognised the other. James certainly did not know who Mr Weatherill was until he was told later. He clutched his head with both hands: 'Oh, no. It wasn't really him, was it?'
In Savile Row, the celebrated bastion of English men's bespoke tailoring, new boys are few and far between. James, 39, is stepping where few have dared to tread before. To make matters worse, he is not even a tailor. He is one of that new-fangled breed of chaps who call themselves - wait for it - 'designers'.
In the late Eighties, Richard James was a hot name in men's fashion circles. He was one of a trio of British designers who staged fashion shows in Paris that excited huge international attention; the others were Paul Smith and Katharine Hamnett. He was rather like the naughty schoolboy alongside Paul Smith. He shared Smith's love of English eccentricity, but he pushed it that bit further, with a range of colours and clashes of fabrics that had rarely been seen before in men's clothing.
James, one always thought, was in danger of being sent to the back of the class. But the store buyers (from New York, Los Angeles, Milan, Tokyo) loved his work. What then happened was a chain of incidents that is wearily familiar to anyone in the fashion industry. James expanded faster than his means allowed, orders mounted up, cash-flow problems developed - and the naughty schoolboy was indeed sent to the back of the class, by his creditors.
This is ancient history now. But moving from fast fashion into the exclusive echelons of Savile Row is not quite as dramatic a switch as it sounds, for he has always considered himself a quintessentially British designer and greatly admires classic British tailoring.
We gave up on the burglar alarm and left it ringing, going round the corner to the cafe at the Museum of Mankind ('It's good, it's cheap, the people are nice') to talk. I had been warned that he liked to drink at lunchtime and that he was garrulous beyond belief. He did not disappoint. 'I don't want you to quote me as slagging off Savile Row. I don't want to end up being the vulgar person in the Row,' he said. 'I love it, everything about the place. I love those old gentlemen with nipped-in waists and narrow trousers. I love everything about English tailoring.
'If there is a difference, it's that I believe that while you should respect the past, you have to push forward, too. People get grouse in Sainsbury's now, not on the moors.'
James will sell ready-to-wear clothes and also provide a made-to-measure service in the best Savile Row tradition. He wants to soften up the structured Savile Row suit, doing away with some of the canvases and interlinings that give the suit its rigidity, and experimenting with colour, fabric, and pattern.
'The true English style is much more eccentric than the French and Italians seem to think. There were some crazy fabrics about in the Thirties and Forties. The idea that the English are always dressed in brown is total rubbish,' he said.
I returned to the shop this week for its opening, and found him darting about with enthusiasm, showing off his lightweight tweed jackets with overchecks of burnt orange and apple green, and soft pink cashmere cardigans to be worn with roll-neck sweaters (the new male twinset). There were multi-coloured square ties, shirts in blue and lilac, and a wonderfully comfortable alpaca overcoat. ('There are more on the way,' he promised. 'I'm still waiting for deliveries.')
There was also some fine and restrained tailoring. James, the arch-colourist, quixotically says he wants to dress head-to-toe in charcoal grey.
Where does James the designer part company with the tailors of Savile Row? 'I'm not keen on the fuddy-duddiness of Savile Row, that snobbery that says you have to wear this type of jacket with that type of shirt,' he says.
'Savile Row does have a problem. The fathers are not bringing their sons anymore. Maybe I can change that because I'm not blinkered. I know about Comme des Garcons and Yamamoto and the other designers. Maybe I can be a catalyst to bring a new generation to the Row.'
The parallel with the late Tommy Nutter is striking. When Nutter opened up shop in Savile Row in 1969, he was like a breath of fresh air, selling a wide-lapelled and big-shouldered look that brought a new kind of customer to the area. He dressed Mick and Bianca Jagger, Eric Clapton, Diana Rigg, Twiggy, even the Beatles (there are three Nutter suits on the album cover of Abbey Road).
The old stalwarts of the Row gave Nutter no more than six months, and watched in amazement as his business flourished. Now the tailors are more wary about writing off James, who could be a worthy inheritor of Nutter's mantle.
Henry Holland, managing director of Kilgour, French & Stanbury, positively welcomes James's arrival. 'It's good news for Savile Row. I hope that like Tommy Nutter he livens up the place and brings in a different type of customer.'
An even warmer welcome has come from Anthony Hewitt, the tailor opposite at number 9. His workshop is making James's made-to-measure suits, and also helping with the manufacture of his ready-to-wear clothes. It is the combination of new-boy design skills and old-school tailoring excellence that really promises something special (Tommy Nutter had a similar partnership for many years with the tailor Edward Sexton).
Hewitt, 57, has worked on and off for years with designers. 'I've always had a deep appreciation of what they're trying to do. Richard's arrival in Savile Row is very encouraging.'
The Row has felt the recession as much as the high street. Earlier this month, Wells of Mayfair, a company dating back to 1829 and once one of the Row's largest tailors, went out of business.
Hewitt is more recession-proof than others in the Row, with a strong following of British customers to counterbalance his export business. Prices for immaculate hand-stitched suits start at pounds 850, and James's made-to-measure suits will be similarly priced. This is a lot of money, but it is a long-term investment: the suit that Hewitt wore for the Independent photographer was six years old, but looked as if it would last for ever.
Richard James, 37a Savile Row, London W1 (071-434 0605). Anthony J Hewitt, 9 Savile Row (071-734 1505).