Oh well, money isn't everything, is it? That's one way of cogitating on the publication each year of the American magazine Forbes's authoritative list of the world's richest men and women. The other way is to slap your forehead with the palm of your hand and rile yourself by considering a few questions; Mark Zuckerberg (Mr Facebook) has made himself £750 million and he's only 23 - how much moolah had I scooped when I was that age? Or, Warren Buffett - investor extraordinaire, and the 21st century's greatest philanthropist - tops the list with a personal fortune of £31 billion: what would the interest on that be - even in a rubbish current account?

The key question, though, is what would you spend it on? Odds are you'd spruce up your wardrobe a bit; maybe some suits from Savile Row, Lobb shoes, and exquisite high-end Italian casualwear worn with aplomb.

But just because you have a billion dollars doesn't mean you look like it. Our jury has assessed six key billionaires' style choices - and delivers some home truths that their yes men never will.

WARREN BUFFETT

Forbes rank: 1

Fortune: £31 billion

Style score: 6/10

Jeremy: The man who now tops the Forbes rich list, and is famously frugal, shouldn't look so cross. His dress sense isn't too bad. The suit fits well, ties are back in fashion, the spectacle frames lend him an air of authority and his shoes are very this season. The only thing that lets him down is the button-down shirt: these look fine with an open collar but worn with a tie, like this, appear a little uncomfortable. The buttonhole is all wrong: the frivolous flower doesn't exactly match his expression.

Sarah: Buffett is sporting the most uncomfortable and doomed-looking corsage in the history of sartorial floral adornment. Plus, of course, an entirely unnecessary name tag. Otherwise, Buffett's chief problem is the ill-fitting button-down collar, its wings gaping unattractively over his tie-knot. He has also loaded up his trouser pockets - perhaps with some spare gold bullion - with the result that his crotch is half-way down his thighs. Nice shoes, though.

MARK ZUCKERBERG

Forbes rank: 785

Fortune: £750 million

Style score: 2/10

Jeremy: Oh dear, it's just all so wrong. He's young and techie, so one can accept that he doesn't have to go the whole hog and don a Savile Row suit, but every element of his outfit is misjudged as well as out of date. If you're attending a conference you need to look as if you mean business. Zuckerberg looks as if he's just come back from a frat party.

Sarah: Geek chic personified. This outfit looks as though it's been scraped off a frowsty bedroom floor before being chucked on in between a bowl of Cheerios and some early morning e-mailing. As for his footwear, sandals like that shouldn't be seen more than 50 yards away from a poolside. The only possible excuse for them is that he's a vegan and he's wearing them for idealogical reasons. He's got nice hair, though. A longer top and shorter sides would give him a better shape, and make the most of his curls. His skin has the advantage of youth - but he should watch out for the sun. Here is a man who really does need to wear sunscreen just to pop out for a coffee.

BILL GATES

Forbes rank: 3

Fortune: £29 billion

Style score: 4/10

Jeremy: These computer geniuses need to discover some better online shopping destinations. Although, to be fair, check jackets and pleated trousers are back in fashion. Sadly, though, his jacket is far too big and those socks look as if they've come from Michael Jackson's Thriller wardrobe. Perhaps Gates was planning to Moonwalk into the Microsoft offices.

Sarah: Worn correctly, the individual components of this ensemble are not disastrous - except, perhaps, the shoes. Basket-weave footwear may just about be acceptable in some of the seedier night clubs in St Tropez, but they have no place on the feet of a computer squillionaire. If they are to be worn, it should never be with socks, especially not white ones. The jacket looks like it could be quite good quality... but dark trousers and a light jacket never work well together and completely smack of Man at C&A. Both the shirt and the jacket sleeves look too long, giving Gates the appearance of a man whose clothes are wearing him, and not the other way round. As for the name tag, surely he's beyond that?

ROMAN ABROAMOVICH

Forbes rank: 15

Fortune: £11.75 billion

Style score: 5/10

Jeremy: While you sometimes wonder if the Russian billionaire would still get past the Stamford Bridge style police if he didn't own Chelsea FC, Abramovich copes with the casual look pretty well. He should tuck the shirt in - makes you appear smarter and slimmer - and the sweater flung over the shoulders is a little bit Eurotrash. Where he excels, however, is the accessories: the slightly weathered shoes are perfect, the chunky watch spot-on.

Sarah: This is not so terrible. Abramovich is channeling the classic Italian-man-at-leisure look: soft brown suede lace-ups, faded, well-fitting jeans expertly trimmed to precisely the correct length, crisp shirt worn slightly awkwardly outside his trousers, expensive watch and, of course, the cashmere jumper knotted casually over the shoulders. My only criticism would be that it's

a bit mummy's boy-ish. A symphony in blue, this outfit signifies that Abramovich is “relaxing”. The slightly pained expression would indicate that this is not necessarily a concept with which he feels entirely au fait.

LAKSHMI MITTAL

Forbes rank: 4

Fortune: £22.5 billion

Style score: 5/10

Jeremy: I'm not convinced by the pastel coloured linen trousers teamed with trainers. It's a little bit Golden Girls. And it's unlikely that someone worth $45 billion is going to be walking that far, so he could easily opt for some grown-up shoes. However, the outfit is neither disastrous nor flashy. Mittal refuses to spend much of his fortune on clothes and believes that Savile Row suits are ostentatious. The most expensive item he's wearing is probably his belt. This is what you call stealth wealth.

Sarah: A hellish Eighties combo of trainers, baggy trousers, floppy shirt and random belt. All that's missing is a jacket with rolled-up sleeves and a flipped-up collar. Mick Jagger just about got away with this look around the time of Dancing in the Street, but as Mittal is proving, in the 21st century this constitutes a full-on fashion felony. Mittal is actually not a bad-looking man. Losing the side parting and over-long fringe would not only make him look younger but also more up to date.

BERNARD ARNAULT

Forbes rank: 13

Fortune: £12.75 billion

Style score: 9/10

Jeremy: The best-dressed billionaire. Here, it's all about luxury as a private pleasure: although there are no designer logos or glistening gold on display, Arnault still looks expensively, as well as immaculately, dressed. The perfectly cut suit (Dior Homme), the spotless shoes (Berluti) - he owns both brands - are set off by the classic white shirt and slate grey tie combination.

Sarah: The perfect outfit. The shirt fits beautifully, with the right kind of collar; the tie is elegant and understated and the suit well-cut and flattering. The trouser legs break at precisely the right point and the shoes are immaculate. Crucially, the dreaded name tag has been replaced by a discreet pin: those who matter know who he is; everyone else is irrelevant.