What to do? Where to look? It is easy enough to scoff at the trashy, celebrity-conscious times we live in, but sudden visitations from the famous can't help being luminous and exciting. They seem to demand something of us. It's a bit like glimpsing a tiger or a shooting star - you almost missed it, and you're not quite sure what you saw, but you want to hang on to the moment somehow. They make us feel simultaneously chic - suggesting that we are moving in the smartest circles - and deflated. Celebrities take their glamour with them when they leave.
I remember a teacher at City University once boasting about such a sighting. "I saw Colin Welland on a bus once," he began brightly, before adding, crestfallen: "Didn't talk to him, though." At the time, we all thought he was being a drip, but in fact he had his finger firmly on the uneasy sadness of such occasions. You feel that they need to be risen to in some way, but how? Would the News of the World pay handsomely for the information that Jerry Hall's friends - perhaps even her notorious ex-husband - can look forward to a chunk of meteorite or a dollop of million-year-old turtle poo for Christmas? Would Jerry be interested in a half of shandy at the pub over the road? Would Jerry like these gift-wrapped (quick, someone: run and get some paper for Christ's sake)?
I suppose that these days we have to call this a classic Notting Hill moment. It was certainly an uncanny echo of this year's hit movie. We were only a short walk from the bookshop where Julia Roberts first smiled at Hugh Grant, after all, and Hall's sudden entrance was an almost exact reprise of the teasing fantasy that made the film so successful. What do you do when a world-famous beauty wanders into your shop? In real life (even in Notting Hill) the answer, of course, is: nothing.
As it happened, the shop wasn't even open. The staff inside were busy preparing an exhibition which opens today. In fact, they very nearly turned away the curious tall blonde visitor by telling her that the show didn't open till the weekend - maybe she could come back then? But such is celebrity: as soon as she had been identified she was welcome (but of course, madam...) to her own little private view. Everyone strained hard to act natural, while (equally naturally) the supermodel snaffled up many of the exhibition's most remarkable treasures before anyone else had even had a squint at them. They all knew that Hall was a rock wife; but who would have thought that the rock in question would be calcite?
Still, it was an uplifting moment for the Hugh Grant of this story, an eager-beaver fossil-hunter called Dale Rogers. For the last decade or so, he has financed trips around the world by running a weekly stall (number 88) in Notting Hill's Portobello Road market, selling ancient rocks trawled from adventures in the fossil fields of Morocco, Madagascar or China. I only live up the road myself, and must have wandered past many times, without (I must admit) feeling the need to push through the knot of crystal-gazers and palaeontologists to fondle the Pleistocene bones and Mexican gypsum on the barrow.
But this weekend's exhibition, his first, is a more ambitious presentation of his 20-ton collection of old rocks. In a gallery borrowed from the war-artist Nik Bashell there are dinosaur eggs from China and sharks' teeth from Morocco. There's a spider preserved in amber, a handful of emeralds, the fossilised horns of a bison, and the fierce jawbone of a mososaur. Some are, oh, half-a-billion years old.
It looked, to my untrained eye, like a sumptuous collection of treasures, the kind of booty you expect would have required complicated expeditions, mounted with the full backing of the Natural History Museum or the Geographical Society. But Rogers, like the great fossil-hunters of the 19th century, is a loner. He grew up in Colchester and fell in love with fossils in Morocco. It has been a hand-to-mouth decade: he has used the market stall to raise just enough cash to fund further trips. "Every time I could afford it I'd go off," he said. "Basically I just like haring around mad places, finding amazing things." It's a low-budget operation. "Christ, it's been ridiculous. I've been driving around the Sahara in a Ford Avenger I bought for pounds 50, with a slab of marble hanging out the back. Or stuck in sand- dunes in a Fiat Uno. But I love it. It's time I settled down, I suppose, but I'm always planning the next trip." He is itching to go to West Timor or Tanzania. "I was in Dar es Salaam recently," he said. "And I thought, everything's here. People concentrate on human remains, the cradle of mankind and so on. But everything's there, everything."
Palaeontology sounds like a dry-as-dust discipline, the preserve of bespectacled scholars. But of course it also has its Indiana Jones resonances, and Rogers does a fair job living up to them. He hasn't studied his subject, but has taught himself Arabic - the Casablancan dialect, handy for dealings with the police. We tend to think of the Victorians as dry-as-dust too, but Rogers reminds us that their global wanderings were inspired by just this sort of hippy travel bug. "My grandfather was in the Raj," he said. "And he collected anything, we had trinkets everywhere. So I grew up with that mania to gather things. I had a quarry in the Sahara once. Amazing place, just this mountain full of great stuff. But now I buy mostly from dealers."
Fossils are not actually all that rare. Millions of them are casually crushed in phosphate or marble quarries - it's too much bother to extract them. You might have a few ground up in your fireplace. The reason they are expensive (the Lyme Regis Ichthyosaurus in the exhibition is pounds 16,500) is that it is very labour-intensive to tease them out of the rock. That is one of the reasons why fossil-hunters head for Africa and China. "They used to use a sculptor's hammer and chisel," said Rogers. "Now they use dentists' drills. But the top guys in Dorset or wherever cost pounds 120 per hour. In Morocco it's pounds 2 per day. Otherwise fossils would be unaffordable."
If life were a movie, Rogers would be slipping into the Ritz by now, or leaping the railings with Jerry Hall in the moonlight. It isn't though, is it?
Speaking of fossils, I went to the annual Varsity match at Twickenham this week. I wasn't the only one. Around 50,000 people paid good money (about the price of two shark's teeth) to watch Oxford and Cambridge continue their 118-year-old tussle. The standard reaction to this is that the fixture is an anachronism: our class-consciousness is such that the game is seen as little more than a picnic for toffs. But as it happens, this is itself rather an anachronistic attitude. It is not as if the game were genuinely a contest between two of our top universities: it is usually a question of whether our South Africans are better than their South Africans. This year, Oxford's captain was from Stellenbosch, Cambridge's from Brisbane.
Not that this is something we need to bemoan, as such. If anything, we ought to wonder why, if the match is so out-of-date, so many ambitious young players from real rugby powers in the southern hemisphere want to come and play in it. Is it really the case that even Oxbridge can't rely on British talent any more? Given the pitch and frequency of the moaning that accompanies each new nadir in the story of British sport, you might have thought we would take such a well-appointed athletic breeding-ground a bit more seriously.
In America, college games between Notre Dame and Indiana command a national TV audience, and pundits fall over one another to spot the stars of tomorrow. The Varsity match, on the other hand, feels childish. Groups from schools chant "Oxford! Cambridge!" in high-pitched voices. A Tannoy asks the schoolmaster from St Neot's to collect Josh from Information. And the programme notes are full of sophomoric quips about how this prop has been turning heads all year, or how that fly-half could fill the stadium with pretty admirers (if only he could be bothered to get out of bed!!!!).
An Oxford man myself, I tried to feel partisan, to punch the air when the dark blues scored. But it wasn't easy. Perhaps, when we berate our sportsmen for failing to project more dynamic images of our nation, what we are truly dismayed by is our own vexed failure of pride.
Fossils and Minerals Exhibition, 275 Kensal Road, W10. Saturday and Sunday