It was here, in the heart of Soho, that a black woman, Celia Johnson- Croft, fell foul of Mezzo's stringent hair code. During an interview for a waitressing job at the cafe bar, which adjoins Sir Terence Conran's flagship restaurant, she was told that her short, spiky braids were unacceptable.
An industrial tribunal rejected Ms Johnson-Croft's claim of racial discrimination earlier this week, ruling that Sir Terence's affluent clientele would expect staff to meet the highest standards of appearance. The tribunal heard that beards and moustaches were also banned.
What surprised some observers about the dispute was that it centred not on the restaurant, a swanky establishment favoured by men in suits, but on the cafe bar, a laid-back place where salads and sandwiches are served by waiting staff in polo-shirts and bright orange trousers.
Nevertheless, Mezzo's hardline stance was applauded by other London restaurants. While hair is clearly a hygiene issue - few diners relish the sight of long locks tumbling into their cassoulets - a stylishly-coiffed look appears to be also de rigeur in places where image is crucial.
"Front-of-house staff should look conventional and blend in with their surroundings," said Marco Pierre White, who runs a string of upmarket restaurants. "My food is served by smart young men."
Dinah-Jane Ladenis, who does the hiring at her husband Nico's restaurants, said that customers expected waiting staff to be spotlessly clean and immaculately groomed.
"Every restaurant has its own house style and staff have to fit in," she said. "I personally would not hire a waitress with dreadlocks or a punky haircut. It would look too different and detract from the ambience. Our image is of a serious eating place with good food and discreet service."
Gordon Ramsay, owner of the Michelin-starred Aubergine, drew a distinction between kitchen and front-of-house staff. "I have got evil-looking skinhead bastards in my kitchen, but upstairs the staff have to be good-looking, soft-spoken and very, very sophisticated," he said.
"Hair should be short, neat and well looked after. It can't spill all over the place, it can't be spiked, it can't be gelled. Big hair? I guess that would be fine as long as it looked smart."
But some of Sir Terence's competitors are more laid-back about hair codes. Stephen Bull, who has just opened his third London restaurant, said: "As a formerly bearded person, I was quite astonished by Mezzo's Stalinist line on facial hair. And some customers think a restaurant is not a restaurant unless the waiters have ponytails.
"In general, restaurants are very conservative places. But I would have been happy to have employed the lady in question. As long as my staff are tidy and unobtrusive, I'm not that bothered."
Extracts from Mezzo's staff grooming code
avoid strong perfumes and deodorants
long hair must be tied back and secured with a black clip, band or ribbon
make-up should look natural
personal jewellery must be discreet and limited to one watch, one ring and a pair of stud earrings; bracelets are not permitted.
black socks or tights must be worn at all times
shoes should be kept polished and in good condition
fingernails must be kept trimmed to a moderate length and only clear nail varnish worn
should avoid strong aftershave and deodorant
beards and moustaches are not permitted for staff in contact with customers
personal jewellery limited to one watch and one ring; earrings and bracelets not permitted
socks must be worn at all times
fingernails must be kept neatly trimmed