It's an exciting moment. The English fashion legend is dressed down today in drab black T-shirt and magnolia shorts. Out of one of the pockets hangs a bill which suggests he has just purchased some cassettes from the shop's bustling music department. While craning to see what the great man's musical taste runs to these days, I suddenly realise I am behaving like a classical Tuscany Brit, foolishly devoted to the comings and goings of other British people while supposedly enraptured by the artistic heritage of central Italy.
The place is full of us. Beside the delicatessen counter, a pair of English ladies gleefully stock up on items for their big dinner party this evening. You can tell their country of origin from a hundred yards away because they are both wearing that uniquely Surrey combination of deck-shorts and pearls. They are inspecting the cheese options. "More taleggio?" says one, "or the pecorino with truffles? Or should we simply go mad with gorgonzola?" "My God," says her friend with the apricot-silk Ferregamo scarf, "isn't that Paul Smith over there?"
In the fruit section, the Italian housewife in front of me is having trouble with the weigh-the-stuff-yourself machine. She plonks a bag of five avocados on the scales and presses the appropriate picture. Nothing happens. The LED screen flashes some complicated Tuscan rubric. "Questa macchina," she tells me helpfully, "e kaputo." ("This car is broken"? Maybe it's some kind of Lucchese dialect). "Never mind," I reply, "there's, er, uno altro weighing machine over by the, er, pompelmos." She looks at me coldly. "Oh," she says, in purest Fulham Road, "Are you English too?"
What can it be that draws us, like Armani-shorted and Speedo- costumed pilgrims, to Tuscany in August? Obviously it's something to do with it being the cradle of the Renaissance and the way you can discover each day a dozen astonishing things just incidentally, glancingly - that, for instance, that bridge outside Arezzo is the one you can make out in the distance over Mona Lisa's left shoulder; that this cool and civilised 150-year-old Caffe di Simo in the middle of Lucca's busiest shopping street is where Giacomo Puccini would pop in for a reviving espresso-and- Danish as a break from composing Turandot; that this boring little town of Collodi is stuffed to the gills with Pinnocchio puppets and sculptures in a variety of sizes because the mendacious, nose-extending marionette's creator, Carlo Lorenzino, was born here; that the original Bonfire of the Vanities took place in this Florentine piazza under the direction of the tiresome Savonarola.
It's oddly comforting to think that the awesome grandeur of high Renaissance art and the epic intrigue of Medici family history can be brought down to a few happy details of birthplace and local site. But the other, parallel attraction may be the simpler one of just sitting here in the garden of a fifteenth-century villa, built as the hunting lodge of the city's former ruler (the original Lord Luccan, indeed), eating strictly authentico mozzarella with fat tomatoes, Tuscan salami and leaves of rucola, passing a fiasco of Chianti around while before you a huge valley spreads out 900 feet below.
At night the valley floor is dotted with twinkling lights, the air is dense with the hornet buzz of courting Vespas and the self-important bonging of the elderly church clock in nearby Maiale, confidently striking six at 1.37. Sometimes - when, say, floating on an inflatable lilo in 36- degree heat, reading the new Barry Unsworth with peach juice dribbling on your chin - it's easy to mislay the noble artistic reasons which brought you here. Mosquitos, lumpy beds and vertiginous clifftop drives notwithstanding, it's still pretty close to paradiso.
As the vacationing British have been discovering for centuries, in their stodgy way. Smollett was terribly rude about Siena because his lodging house smelt funny. Shelley came to the lovely spa village of Bagni di Lucca and ignored the locals, preferring to sit reading Herodotus on the rocks by a forest pool. E M Forster mocked the English bourgeois who came to Tuscany looking for art and, when confronted with nude statues, thought them "a pity". More recently Sir John Mortimer defined the English colony of middle-class expatriates as "Chiantishire". And now, of course, our presiding angel is Tony Blair, who arrived here on Saturday with his family and is staying at a pounds 9,000-a-week villa in San Rossore, west of Pisa.
He has run into trouble, the manufactured, silly-season variety, from people who complain that he shouldn't have accepted a free holiday and 100 Italian security men from the President of Tuscany (wouldn't you?), and from locals who objected that a three-mile local beach had been closed to give the Blairs private access. The Blairs got it reopened for the Italians to use. What he should have done, of course, was demand exclusive beach rights for British holidaymakers, since it's virtually impossible for non-Italians to get within snorkelling distance of any of the beaches around Viareggio.
You can detect a little frisson among the Brits in the Esselungha supermarket at the prospect of their beloved leader following the same itinerary as themselves. Would they rub shoulders with Cherie in the oil'n'cheese cantina? Would they find the PM queuing in the farmacia for some hornet-sting ointment? Would their children encounter young Euan Blair cycling round the walls of Lucca and invite him over to try their diving board? Would Tony himself appear (with or without his minders) in the heart of Pisa, braving the crowds circling the Leaning Tower and looking for the famous cioccolateria which sells chocolate chickens and monkey wrenches? Would he just drop by one afternoon, for a slug of Limoncello and a whack at our ping-pong table?
No, he won't. The Blairs are famously reclusive on holiday. They are not enthusiastic wanderers through the streets. "He just wants to relax, enjoy the beach and go horse riding," a Downing Street person informed the media. Next weekend the family will be staying in an even more impossibly grand mansion owned by Prince Girolamo Strozzi just outside San Gimignano. Having (mystifyingly) received no invitation from the Prince myself, I paid a visit to the town anyway - and discovered a rather touching shrine to the PM right in the heart of it.
San Gimignano is a holy city, known since the Fifties as "the medieval Manhattan" because of the 70 tall towers that used to dominate its skyline. There are only 14 of them left, but they are impressive still. In the town centre, the Piazza del Cisterna, you find a superior ice-cream parlour run by Sergio Dondoli, a moustachioed cove who looks like the villain in a Chaplin movie and makes award-winning gelati for special occasions and special people. A bit of a celebrity-hunter, S. Dondoli festoons the walls of his shop with pictures of famous customers: cosmic figures from Italian politics, TV stars, pop stars - there's even a blurry snap of the Russian sage Alexander Solzhenitsyn in unbuttoned mode, apparently contemplating a double scoop of banana and tiramisu. And in pride of place on the wall is a letter from Tony B, dated a few months back. "I just wanted to write and thank you very much for the ice-cream that Fr Jim delivered on your behalf," it reads. "I understand you created this specially to honour my visit and as an expression of gratitude for my efforts to obtain peace in Northern Ireland. This really is most kind of you and I am very grateful. Molto grazie, Tony Blair."
Tantalisingly, S. Dondoli doesn't reveal the flavours that went into his anti-sectarian dessert (Republican pistachio with Unionist orange, swirled round in a sort of Paisley pattern?) but he's clearly a big fan of Mr Blair. The letter is framed alongside with a photo of the PM, and English tourists are laughingly directed to examine it. It would be a shame if the great man didn't pop in to say "Ciao" to the reverential Sergio when he's in town on Saturday. And the "Fr Jim" reference? That's Fr James Wetzel, the Roman Catholic pastor of San Gimignano, who, apart from delivering ice-cream across Europe, also furnishes Tony and Cherie with reading matter (as a nearby copy of the Express reminds you). He has enjoyed religious discussions with Tony in the past, shares with him an interest in St Augustine and pressed upon him a copy of the Confessions last summer.
So there you have it. That's life in Blair-land. A nine-thousand-quid villa, a hundred Tuscan flatfeet, as much Irish-themed ice-cream as you can eat and a fifth-century work of controversial theology - all absolutely free. There are some mornings, I'm sure, when Tony just can't believe his luck.