After all, tennis is awash with money. This year's Wimbledon men's champion will receive �700,000 . . . even the first-round losers bag �10,000 . . . making it almost a moral obligation for the sport's leading consorts to outbling and out-couture their footballing counterparts.

Given all that, it may come as some surprise to learn that the current top Twag . . . Miroslava 'Mirka' Vavrinec, girlfriend of world number one Roger Federer . . . is nearer Laura Bush than Victoria Beckham in-waiting when it comes to style cues. Yes, she's nuzzling up to Federer in Prada and Dolce & Gabbana, complete with big-ish hair, in the current issue of Men's Vogue, but Mirka, a former player who is now Federer's business manager and agent, insists that her job isn't to upstage him: "I'm no crazy, disco-dancing girl who drags Roger shopping, " she insists. "I like fashion, but I am the complete opposite of that."

It turns out that Mirka is toeing a tacit Twag nonCristal-swigging, nonKarl-Lagerfeld-corset-sporting, keeping-the-head-down party line.

Kim Sears, 19-year-old girlfriend of British number one Andy Murray, is an aspiring actress and is rarely mentioned in the press without the epithet "stunning" appended, somewhat histrionically, to her name; as a Wag she'd be besieging Celebrity Big Brother bookers and going commando at film premieres, but as a Twag she applauds dutifully in players' boxes worldwide, dresses in nondescript jumpers and jeans, and says things like "I'm not interested in cashing in on Andy's fame; it's not about me. It's all about Andy."

"This isn't just a fashion thing, " argues Kate Bussman, features editor of InStyle magazine. "It's a cultural thing. Tennis has traditionally been a much more middle-class kind of sport than football, and the unwritten rule has been to avoid vulgarity and practice stealth-wealth; the classic 'look' for a Twag is that well-groomed, Sloaney, 'born to it' kind of look.

Their idea of cutting loose is usually just a little black cocktail dress."

Tennis insiders agree that Twag mufti is as traditional to the sport's image of itself as massively overpriced strawberries. "There was a brief playboy moment in the 1970s and 1980s, when John McEnroe dated Tatum O'Neal and a few lesser Twags acted like movie stars, " says Justin Gimelstob, a former player who now operates an often scurrilous tennis blog from the sidelines of the major tournaments.

"But historically, players have been totally focused on success on-court and completely uninterested in all the hoopla off it. This is drummed into them by their coaches and agents, who don't want them associated with partying or premiereing.

"The last thing you need in these circumstances is an extrovert Twag who's intent on making headlines of her own. And let's face it, most of the top players are such egomaniacs that it suits them fine to have the spotlight trained on them and them alone. Look at Steffi Graf . . . she was obviously a superstar in her own right, but as soon as she married Andre Agassi, she was slipping in through the back door of Wimbledon in a pleasedon't-notice-me kind of way. It's just one more factor that's contributed to making the game so dull." (It's notable that the game's current sole throwback to the days of Big Personalities alongside Big Serves, the mercurial Russian Marat Safin, travels with an attendant retinue of dusky Slavic devotees who've been dubbed the Safinettes).

Far better, received wisdom runs, to have a Lucy Henman behind you . . . impeccably Home Counties in her sober jackets and sensible shoes, never succumbing to vulgar displays of emotion, once (favourably) compared with Joan Hunter Dunn . . . than a Lucy Rusedski, who blotted her copybook by wearing lipstick that was just a little too scarlet and fronting the likes of Channel 5's Trust Me, I'm A Holiday Rep. It's a lesson that Lleyton Hewitt's wife Bec Cartwright has inwardly digested . . . a former Home and Away actress and pop star, and once voted the sexiest woman in Australia by FHM readers, she now spends her time stressing her keen interest in modern art. "She likes photo-realism, " offered one gallery owner she visited during last year's Wimbledon. She's unlikely to be brandishing Damien Hirst's diamond-encrusted skull any time soon.

But there are exceptions . . . those the tennis bloggers who have a tendency toward the overexcitable call the 'Alpha-Twags' . . .

who chafe against the greige-twinset restrictions. These include James Blake's girlfriend Jennifer Scholle, a model blonde who's posed semi-naked for Maxim;

Fabrice Santoro's wife Chrislaure, a former chorus girl;

and Guillermo Coria's wife Carla, a Croatian who resembles a Mexican soap-opera actress. Particularly harsh bloggers have said that her make-up arrives 15 minutes before she does.

"But have you noticed something about these guys?" says Gimelstob. "They're all stuck or falling down the rankings, while Rafael Nadal, who has a demure and practically invisible 18-year-old girlfriend named Xisca, has soared to the top." That's why, he suggests, Wimbledon Wags are actually Twaglets . . . 'Tennis Wives And Girlfriends' who show unflashy 'Loyalty' to their 'Eminent' partners because they know which side their 'Toast' is buttered. "It doesn't scan, " he acknowledges. "But it's more accurate."