London's upper lip trembles as Yankees nose into Sotheby's

Going, going. . . . Another bastion of the British way of life is under threat. Sotheby Parke Bernet, the 250-year-old fine-arts auction house may itself come under the hammer, after one of the longest and most vitriolic takeover battles ever witnessed in the fine-arts world.

To the dismay of its management, the ailing London-based company may pass into the hands of a couple of young American financiers-turned-industrialists, Marshall Cogan and Stephen Swid. The Sotheby board has contemptuously described the pair as ''totally unsuited'' to the task.

Tempers have become so frayed, and the issue so sensitive, that the British government has been forced to step in and refer the (STR)61 million ($92 million) bid to an antitrust body, the Monopolies and Merger Commission. The bid will be frozen for up to six months, until the commission decides whether such an important national asset can be allowed to fall into foreign hands.

This is a setback for Cogan and Swid, who may retain the 29.9 percent of Sotheby's stock that they had acquired on the Stock Exchange. But they must return the shares offered to them after April 14 - which they estimate to be between 60 and 75 percent of the total stock - until the commission decides whether to let the bid go through.

London has watched the unseemly squabble for control with fascination. As one financier remarked, with the American TV show ''Dallas'' in mind: ''From the way the British establishment has reacted, you would have thought it was a case of 'JR' bidding for the crown jewels.''

Sotheby's, which with Christie's and Phillips dominates the international auction market in antiques and works of art, has always prided itself on being rather more than just a business. Its employees generally are part of the same elite that form its clientele, and many were born in the kind of stately homes whose contents they now sell. Contacts are made through the old-boy network and it is not uncommon for million-pound deals to be clinched in some exclusive gentlemen's club in Piccadilly.

It is this unique style that has made Sotheby's a favorite haunt of connoisseurs and down-at-heel aristocrats selling off their heirlooms. Such is the firm's status that even Princess Margaret used it not so long ago to sell off what one employee coyly described as ''a few bits of jewelry.''

Sotheby contends these delicate but essential links would be severed if Cogan and Swid gain control. Sotheby's chief executive, Graham Llewellyn, is appalled at the prospect: ''I'll blow my brains out if the Americans succeed,'' he said. His outburst set the tone for Sotheby's counteroffensive against the bid, which to many smacked of snobbery and arrogance.

But the man in the street has been left wondering what the fuss is about. After all, the majority of Sotheby's shares have long been in a variety of American hands and the credentials of Messrs. Cogan and Swid seem perfectly sound: They control the world's largest maker of carpet underlay (General Felt Industries) and GFI/Knoll, which makes fine and expensive furniture. They also boast some expertise in the art world: both are collectors, who between them hold a number of trusteeships and advisory posts with leading museums, including the Guggenheim and the Metropolitan Museum of Art in New York.

But this cuts no ice with Sotheby's.

''They make top furniture, but what has that to do with us,'' asked Mr. Llewellyn, who is a jewelry expert. ''These Americans come from the manufacturing sector and if their bid succeeds, the nature of the company will be changed. They are simply the wrong people,'' he sniffed.

Many of Sotheby's distinguished staff of experts at first appeared to agree, though they had never met the Americans face to face. More than 130 of them wrote a letter to the prospective buyers threatening to resign en masse if the deal went through.

The obvious danger was that they would join one of Sotheby's rivals or set up a new auction operation, taking their clients with them. The Americans' suggestion that the staff might be interested in a profit-sharing plan was met with disdain: As one Sotheby expert said, ''Although pay is low, many staff members have private incomes. They would have no use for a scheme of this kind.''

Continuing their efforts to discredit the American bidders, Sotheby's darkly hinted that Mr. Cogan had a skeleton in his financial cupboard. As they pointed out, he had had a brush with the Securities and Exchange Commission back home in 1969. Was this the kind of man, they implied, who should take the helm of such an august institution? The Americans, unflustered, replied it had been a minor matter and that Mr. Cogan had never been convicted of anything.

Finally, the Sotheby board asserted that the Americans were financially overstretched. And here, many observers felt they had a point. Cogan and Swid have had to borrow heavily from American bankers to finance the takeover, and if anything went wrong, Sotheby said, the firm's future could be in jeopardy.

Messrs. Cogan and Swid have been visibly taken aback by the personal tone of Sotheby's attack and the ferocity with which the old company is fighting to keep them out.

''We have been treated like pariahs,'' they said. ''Sotheby's board has done everything possible to intimidate us.'' They complained that they had been unable to put their case across to Sotheby staff, because the management had barred them from meeting anyone on the ''inside.''

''Sotheby's experts do not accept items without looking at them personally,'' they said, ''yet none of the experts have been allowed to look at us.''

But instead of rising to Sotheby's bait, Cogan and Swid disarmed the British public by displaying the kind of courtesy and gentlemanly restraint formerly associated with the Bond Street elite. They stressed that their intentions toward the auction house were honorable.

They recognized that it was a unique institution and vowed to keep its headquarters in London and the majority of the board British. They even managed to beat the opposition at its own game of one-upmanship by announcing that they had lined up a peer of the realm, Lord Harlech, to serve on a reconstituted board. All they wanted, they were at pains to point out, was to impose better management and help Sotheby's regain its preeminence.

In fact, the Americans' offer was regarded in the city as rather generous for a business that has clearly fallen on hard times, registering a (STR)3 million pretax loss last year. As the president of the British Antique Dealers Association, Charles Lee, commented: ''They have been thrashing around rudderless and have behaved with an extraordinary degree of arrogance, pretending nothing was wrong.''

Even some of Sotheby's staff, alienated by the management's haughtiness and questionable tactics, have recently come round to the American's way of thinking. Several have indicated they will stay if the takeover is successful.