Tom Stoppard stares at a piece of chocolate. His ex-wife Dr Miriam dissects another with scientific rigour, and they confer in a whisper. The director Richard Eyre nibbles thoughtfully before scribbling down a verdict. Peter Mandelson sits silent - he does not do chocolate. Nick Hornby, having just published a best-seller featuring a small boy, might be expected to know a thing or two about sweets. But like Jeremy Irons and Doris Saatchi, he is stumped by the fifth sample.
The blind tasting is one of the more unpredictable questions thought up by Gill Hornby and her team for an event that is rapidly overtaking charity gala dinners and auctions in the social calendar.
This is the pub quiz for the chattering classes, the perfect opportunity to show off your knowledge and raise money for charity. But the high calibre of contestants and their naturally competitive streak introduced an edge of desperation quite out of place at an amateur event.
The standard is suitably high for an event at which Jeremy Paxman asks the questions and Jon Snow gives the vote of thanks. Before we got to the taste test, we had identified the first and last doges of Venice, pinned down snatches of political speeches and shipping areas on maps, decoded long-forgotten chemical formulae, remembered (or not) the number of stomachs in a cow. My husband earned his stripes by informing us that "Bob's your uncle" first came into common parlance when Arthur Balfour became a minister under Lord Salisbury, aka his uncle, Robert Cecil.
The elegant Ms Hornby whisks around, switching on archive recordings and presiding over the final court of appeal. "What is the name for people from Newcastle-upon-Tyne?" asks the question master, Jeremy Paxman. "I'm not accepting `Geordies'," says Gill. (Novocastrians, since you ask.)
The quiz was started three years ago by the author John Mortimer and his wife Penny, to raise money for deprived children, and now the pounds 100 a head tickets for the evening - this time in aid of Treehouse, a charity that provides schooling for autistic children - are snapped up.
For a too brief while, our table, which includes John Venning, head of English at St Paul's School, and Joyce Hytner from the Royal Court Theatre, remains in contention, sustained by history, politics and literature. Then disaster strikes, with the law round.
Our collapse continues with the science questions. Then all hope is dashed by the comedy round. "Don't worry," says my neighbour, "No one here watches television." The questions that stump the whole gathering are instructive: last year, no one knew the basic rate of income tax.
But it turns out that some contestants do know the name of Raquel Trotter's daughter in Only Fools and Horses. A really crack team would never leave such a vital flank open. Publisher Neil Mendoza appears so bent on victory that you wonder whether, like the England squad, he gave up sex and baked beans to achieve it.
Behind the social babble rage violent competitive passions. Mendoza's team features his business partner William Sieghart, the drama critic and Renaissance man John Gross and the Spectator TV critic James Delingpole. They won the first quiz three years ago and lost last year to a team featuring Robert Harris, the novelist and husband of Gill Hornby.
Gross felt that the combination on one team of the question setter's spouse and her brother raised questions of quiz insider-trading. Rivalry is still intense. This year, Mendoza's team beat a Harris, Hornby and Mandelson into third place.
"We were so excited that having to stop for dinner was a real blow," says Mendoza. "The adrenaline and bile directed at us throughout the evening were incredible." To make themselves even more unpopular, in the interval the team worked on another, postal quiz to keep their momentum going.
The thoroughly English, more-important-to-take-part-than-win attitude of the contestants on such occasions rebels against those who treat an amateur pastime as though it were a professional matter.
It seems strange that people who spend their working life striving for prominence in pressurised, competitive situations are gagging to spend a summer Sunday night doing exactly the same thing. Or maybe not.