Bacon had an international audience almost from the start of his career; in fact, Peppiatt points out that collectors abroad seemed to appreciate his work before those at home. In contrast, although the others have had buyers outside Britain, their collectors have been more local. Secondary-market dealer Ivor Braka, who has handled School of London artists for some 30 years and says he has "sold more Bacons and Auerbachs than anybody else, aside from the primary galleries," believes that it wasn’t until 1992 that a major change occurred in this situation.

"What springboarded the whole thing was Bill Acquavella taking Lucian Freud," he says, adding that when the Metropolitan Museum then exhibited the painter in 1993, it was "a wake-up call for American buyers." The raised awareness of and prices for one School of London member served as a sort of pulley system, hoisting up the rest.

"Bacon's prices have escalated the whole group's," says Ordovas. Interest in that artist's work increased international awareness of Freud, for many years Bacon's friend. Freud's pictures in turn opened eyes to the output of Auerbach, of whom Freud is a great booster. That led to greater appreciation of Kossoff, Auerbach’s friend from art school (although Kossoff's often thickly impastoed work is generally offered in British modern rather than contemporary sales, indicating that he hasn't yet reached his colleagues' level of international recognition). So far, Michael Andrews appears to be the odd man out, despite the poetry of his often thinly painted landscapes of lushly green Scottish estates and Australia's arid, red Ayers Rock.

At the beginning of his career, Andrews, like Freud, sold to a small group of friends—aristocrats, landed gentry, industrialists—who would never have a financial need to sell. Unlike Freud, his patronage never expanded much beyond this circle. Probably the biggest reason for this is the small number of pictures he finished. Helen Lessore noted that in the 20 years following art school, he completed no more than one large work a year. As a result, should an Andrews come on the market privately today, people would have no idea how to price it.

In contrast, Auerbach, Kossoff and Freud—although prolific only when compared with Andrews—have unquestionably each completed enough works in their long careers to establish market values. The first big leap in those values took place almost exactly a year before the record-breaking auctions of this winter, and it set the tone for all that followed.

In February 2006, Christie's London sold "The Collection of the Late Miss Valerie Beston: Artists From the London School." Although many of the pictures were small, almost everything was fresh to the market and choice. Miss Beston, as she was known, spent her entire working life as a gallery administrator at Marlborough Fine Art, which was Bacon's dealer from 1958 until his death, in 1992; it also handled Freud for a time and Kossoff briefly and has represented Auerbach since 1964.

Beston formed a strong bond with a tiny group of artists she admired, Bacon above all. Many of the lots in the sale were gifts to her, including Bacon's sad, puzzled self-portrait. It fetched £5,160,000 ($9 million) against a high estimate of £1,800,000 ($3.2 million). Auerbach's jagged, electric 1986 Tree on Primrose Hill went for £433,600 ($755,800), against a high estimate of £100,000 ($177,200), and Andrews's 1968 Study of a Head for Lights, a seven-inch-square portrait of a full-lipped, androgynous youth, sold for £176,000 ($306,800) against a high estimate of £60,000 ($106,300).

"Everybody perceived the Beston sale as the break-open for Bacon and Auerbach," says Oliver Barker, head of contemporary art at Sotheby's London.

The sale also set a world auction record for Andrews. It did not, however, include any Kossoffs, whose works in general have seen more action privately than at auction. "It is not a secret that his auction prices have been below the gallery list," says Braka.