We're only here for the beer

Like a child in a sweet shop, I won't know where to start. Candy being dandy, but liquor quicker, I shall be confronted not with sweets but with 500 lagers, wheat beers, ales, stouts and such nectars. They will all be on sale at modest prices (by London standards) in the great glassed and girdered exhibition halls of Olympia from next Tuesday.

Maybe I should begin by trying to find the best lager? The too-obvious choice would be the sweetish, rounded, Budweiser Budvar, but this enlightened Bohemian brewery is also sponsoring some of its competitors on the Czech beer stand. Perhaps the crisp Bohemia Regent or the perfumy Lobcowicz lager?

I was mulling over these thoughts when accosted by a spectre in a backward baseball hat and a Union-flag vest: "I thought you didn't like lager. You hardly ever write about it."

It's the tasteless ones I dismiss. In the Czech Republic and Bavaria, I drink the local lagers, but the best rarely make it to Britain.

"So, any good Bavarian lagers at Olympia this year?"

Andechs Hell, a rich-tasting golden lager from a Benedictine abbey; Augustiner, the lager most highly regarded by the people of Munich; or the faintly smoky, dark lager from Regensburg's Kneitinger brewery, operated by a charitable foundation to benefit orphans and sick children.

"Nice to be benevolent... but how can lager be dark?"

Lager can be any colour. The original ones were brown and some of the most fashionable ones in Germany at the moment are almost black. The term "lager" has nothing to do with colour. It means a beer that has a cold maturation.

"Is that a good thing?"

The cold maturation gives a true lager a clean background, highlighting malty sweetness and hoppy dryness. The ale family, matured at warmer temperatures, have more complex flavours, which can be more individualistic.

"But those fashionable Belgian lagers are full of flavours."

Not all foreign brews are lagers. Brews like the quenchingly citric Hoegaarden, the strong abbey-style products from Leffe and the port-like Chimay Trappist are ales.

"So they'll be at Olympia?"

Not only Hoegaarden. A whole bar will be devoted to Belgian-style, coriander- tinged wheat brews, often known, because of their pale colour, as "white" ("wit", in Flemish) beers. This is a new feature this year. We are promised about 50 examples, from the Dutch Korenwolf ("Hamster"), to the British Fenland Sparkling Wit, to the American Vermont Dim Wit. You'll find Belgian Trappist beers, too, like the intensely dry Orval and the chocolatey Rochefort, but also an aniseedy abbey-style ale from the new Ommegang brewery in New York.

"Beers from all over the world?"

If you want to taste classic beer styles from the great brewing nations, no festival anywhere else in the world comes close.

"Not even the Oktoberfest?"

That famous Munich fest has a grand total of eight beers. Millions attend, but it's the old style of beer festival. (It dates from 1810, after all.) This event at Olympia, dating from the late 1970s, is a celebration of diversity. Close on 50,000 thirsty people will go there.

"What's it called? The World Beer Festival?"

No, The Great British Beer Festival. As well as 200 foreign beers, there are more than 300 British ones.

"I didn't know Britain had that many beers."

The number of breweries has tripled in the past 30 years. Britain has 350 tiny breweries dating from that period, despite a few sad closures this year. Some newcomers have seen spectacular successes in the annual judging at the festival.

"If this festival is that good, why don't I know about it?"

Because in Britain we mock anything done well. Check out the press pictures on opening day.

"What will they show?"

Fat men with beards and sandals.

"Who will really be there?"

Certainly some beards and sandals, but also women with neither, lots of Americans, the odd Japanese.

"So why have we spent all this time talking about foreign beers?"

I've been trying to retain your interest. People who wear Union-flag vests usually drink beer that they think is foreign.

" 'Think' is foreign?"

A great deal of the "foreign" lager sold in Britain is made in places like Mortlake and Manchester.

"So I'm already drinking British?"

Yes, so why sell yourself short? Try something with flavour: the aromatic Adnams Extra; the hoppy Badger Tanglefoot; Cain's well-named Formidable... .

"Is it all bitter?"

Some bitters live up to the name; others are far sweeter than they sound. Some of the world's most bitter brews are lagers. All lagers, wheat beers, ales, etc, have some appetising bitterness to balance the sweetness of the malt. The bitterness comes from the hops. At the festival, you will find British Bitters, Mild Ales, Summer Ales...

"Are they all dark?"

Gold, amber, bronze, copper, mahogany, ebony. Why are you afraid of the dark?

"Because dark beers are thick, filling and strong."

There is no connection between colour and either body or strength.

"So what's your favourite beer for drinking at the festival?"

None. I'll be looking for new beers. That's the whole point.

"And if I buy a beer and don't like it?"

Keep trying. No pain, no gain.

The Great British Beer Festival opens to the public at 5pm on 3 Aug, and keeps old pub hours until Friday and Saturday, when it is open all day. Details and ticket prices: 0870-904-0300 or www.camra.org.uk