Or you're in Venice - all you've seen is the train station and the small vaporetto that has taken you to a restaurant on the Giudecca. Now you're picking your way, at midnight, along the dark, canal-side walkway. You cannot see it, but the gleaming white meringue of the Santa Maria de la Salute church is looming somewhere overhead, obscured by roofs; at any moment, you'll walk out on to the tiny triangle where the Giudecca and the Grand Canal converge and, from Campanile to islanded Cipriani Hotel, the whole majesty of the Serenissima, its harbouring walls littered with bobbing gondolas, its windows hung with globe lanterns and strewn with a million secret fires, will rise up in front of you like a magnificent dream. You take a step forward, peer round the corner and...
You know that feeling? It was a bit like that at the wine-tasting.
"Come down," said Andrew Lloyd Webber on the telephone a few days earlier. "I'm having a tasting of the '82 clarets. Serena will be there." This is not an invitation to be taken lightly. I'd been intrigued by recent revelations about the friction between rival Masters of Wine at the nation's leading auction houses, Sotheby's (Serena Sutcliffe) and Christie's (Michael Broadbent).
Shocked to discover that the latter had called the former "pretentious", I'd written a piece in defence of pretentiousness. Lord Lloyd-Webber had read the article and, from either devilment or simple generosity, asked me to join the warring parties in sampling the most contentious of claret vintages - the 1982 - at his simple pad near Newbury in Berkshire.
Michael Broadbent couldn't make it, so the spectacle of duelling palates wasn't the main attraction. But Serena Sutcliffe was there, a severe- but-sexy dream in brown suede jodhpurs and American knee boots; and Marco Pierre White was there (a vast and frankly menacing figure in Medusan black curls and green tweed jacket); and Matthew Freud, the millionaire PR mogul who co-owns the Pharmacy restaurant; and Lindsay Hamilton, the Pimlico wine merchant; and David Mason, Lord and Lady Lloyd-Webbers' straight-talking art buyer, whose Victorian and pre-Raphaelite purchases line the wall of the dining-room, glowing with an unearthly light as if their artists had returned from the dead, and had re-buffed them that very morning with tiny brushes.
The wines were arrayed on a long table, 17 of the 1982 clarets, each with an attendant flock of glasses, one slug judiciously poured out for each guest. Bowls of savoury biscuits stood by for those whose taste-buds were flagging. But how could they flag? For this was an oenological battleground. We weren't there to flatter our host about the excellence of his cellar. Andrew Lloyd Webber is a serious wine buff, but he is keen to show his independence from the received wisdom of transatlantic connoisseurs (such as Robert Parker the American know-all, who awards marks out of 100 to Big Wines and who gave some of the '82 vintages scores in the high nineties), or the cooing reassurances of French grand cru vintners. Though he sold a hefty slice of his collection through Sotheby's last year, he is not to be taken in by excitable tasting notes from the likes of Sutcliffe and Broadbent.
He was suspicious, he said, that all was not well with the '82s. He thought some of them decidedly thin and dodgy. The fact that he owns several hundred thousand pounds' worth of the stuff didn't mean he was blind to its shortcomings. He was, I suspect, a bit miffed that Auberon Waugh had written a piece in The Spectator on 26 September, pouring scorn on the 1982 vintage - The Chateau Leoville-Les Cases, according to Waugh, was "a thin, short, defeatist little wine, with nothing more to come out of it".
"Defeatist", eh? Could we match Mr Waugh's elegant scorn? Could I, more to the point, find anything to say on the matter? I, whose appreciation of wine stops at Sainsbury's Nuits St Georges for big occasions, and Chateauneuf- du-Pape for Sunday lunch?
The tasting began. We shuffled round the table like monks around a cloister. The Montrose was, I noted, "plummy on the nose, flat as a flounder on the palate". The La Lagune smelt OK, but was (can I believe I wrote this?) "short as a Finnish night". "No good, no good", said Lloyd Webber. "It's just not going anywhere." The Ducru-Beaucaillou had sweet undernotes (sweet claret?), but everyone noddingly agreed that it would "improve'. The Lynch Bages was soft and yummy and smelt of hay, while the Cos d'Estournel was "disastrously bitter and medicinal". One guest gushed, "I've just tried the Pichon Lalande, and it's a very pretty little girl."
But despite such sentiments, and the presence of Miss Sutcliffe, who once detected the essence of "Cairo spice bazaar" in a Romanee Conti burgundy, few seemed keen to utter the risky adjective that supposedly characterised these proceedings. The lady beside me was marking everything out of 100, in the style of Robert Parker, which always seems to me a pointless way of assessing wine, while others stuck to safe utterances about "lots of tannin", and "acid balance".
Serena was streets ahead of the others, commenting (on the Waugh-derided Leoville-Les Cases): "There's a lot of oak - even though he doesn't use much oak in his barrels." As we moved on to the gorgeous pounds 1,000-a-bottle Chateau Petrus, she swirled it around the glass and remarked on the glycerol that made the expensive residue stick to the side. Now this, I thought, was real connoisseur shit - to ignore its smell and taste and concentrate on its stickiness.
We moved on, the wine merchant noisily slooshing every glassful through his tongue, the other guests saying little beyond "this is the second '82 Lynch Bages I've had this week, you know". Miss Sutcliffe became more adventurous, identifying, for instance, "a very lead-pencil smell", and "that distinctive cigar-box underlay that not everyone likes".
I tried to join in. "Serena," I said, my nose in this Cheval Blanc. "I think this is terribly... choir loft, don't you?" She regarded her glass sternly. "No, John," she replied. "It's mostly fruit, but the final taste is coffee."
And then there was the final burst towards the finishing-line, with only the Big Four up ahead. Before me lay the Holy Grail of the Grands Crus Classes, of which I'd previously only heard rumours, but never dreamt of trying: the '82 Lafite, Latour, Margaux and Mouton Rothschild. Unlike Venice, unlike the Sistine Chapel, they looked quite normal - just sitting there in ordinary bottles, but harbouring the final secrets of human taste- buds' bliss, the paradise and Ithaca of any wine-lover. What were they like? They were wonderful, yet they were oddly pedestrian.
You gathered the glass up to your nose and smelt what should have been ambrosial, rapturous, vanilla-and-honey-with-angels'-wings... and the wines just refused to be anymore than good wines. Sure, they were sophisticated, smooth beyond belief, and more "complicated" in their texture than the other clarets. But they refused to yield up any massive secrets.
And then I tasted the Chateau Latour, and began to tingle from head to foot. It lay on my tongue like a dream, spread itself languorously to the corners of my mouth, and took off in a million directions at once.
"Bloody hell," was all I could say. The wine merchant looked up. "Incredibly long finish," he observed. "That's the secret. That's where the money is."
And I only realised that it was the best wine in the world because, for the first time, all the adjectives deserted me.