Eight years old and four feet tall, Sasha Coulson stared with wonder at the price tag for Damien Hirst’s gold-accessorised bullock in formaldehyde yesterday.

“Eight. . . million to. . . twelve. . . million pounds,” she read out loud, scarcely able to believe her eyes. She looked hard at The Golden Calf again before reaching a verdict on the art world’s question of the moment. “It is quite cool.”

The calf is expected to be the most expensive lot out of 223 set to go under the hammer at Sotheby’s tonight and tomorrow afternoon in a pioneering auction made up entirely of new work by Hirst. Whether the sale meets its expected £65 million take or not, whether it enhances or damages Hirst’s reputation and whether any other artists could dispense with their dealers will remain matters of fierce debate until the bids start.

What is no longer in doubt is that the sale, entitled Beautiful Inside My Head Forever, has captured the imagination of an audience far bigger than the usual art-collecting crowd, with rock stars, Wall Street traders and the general public all keen to share in a moment of history.

Sasha was one of a record 19,000 visitors to Sotheby’s New Bond Street headquarters in Central London over the past nine days. Yesterday the queues were so long that Sotheby’s opened an hour early and on Saturday did not shut until midnight.

Cheyenne Westphal, chairman of contemporary art for Sotheby’s, Europe, said the show was the biggest exhibition of Hirst’s work. “We wanted to show it as an exhibition because although Damien has had lots of offers he has never agreed to a major retrospective. He doesn’t feel old enough.”

She estimated that up to 3,000 prospective buyers had seen the work. On Friday night a private party to mark the sale was attended by the rock stars Bono from U2 and Flea from the Red Hot Chilli Peppers, the actor-director Kevin Spacey, and Daria Zhukova, the girlfriend of Roman Abramovich, who has just opened a gallery in Moscow.

The demand is a fillip for the auction house after its share price fell 8 per cent on Thursday, fuelled by fears that the sale will flop because the artist has saturated his market. The stock recovered on Friday.

Hirst has been a regular presence at Sotheby’s in the past week, meeting potential buyers. He has admitted, however, to nightmares about the gamble he is taking, telling one interviewer: “I imagine it going: ‘Lot 9 — no bids. Lot 10 — still no bids.’”

The world will find out tonight.

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