British Prime Minister Margaret Thatcher, who was born in the small flat above her father's grocery store 58 years ago, has always said she never minded "living above the shop."

So it was no surprise in 1979 when, a month or so after her election, she and husband Denis moved the few miles from their home of almost 30 years in London's Chelsea section into the small four-bedroom apartment on the top floor of 10 Downing St.

Thatcher's Labourite predecessors, Harold Wilson and James Callaghan, had chosen not to live atop the bustle of the famous Number 10 -- which houses, downstairs from the official residence, the cabinet room and offices for some 150 advisers, civil servants, secretaries and guards. But the new conservative prime minister seemed to enjoy it.

Now the family has put the small, neat three-story row house (attached on both sides) at 19 Flood St. in Chelsea up for sale. A spokeswoman for the firm of Keith Cardale Groves, which is handling the sale, says the company has "been instructed not to talk to the media" about it.

But local real estate agents say that when the house came onto the market several weeks ago, it was established that only bids "in excess of 250,000 pounds" in British sterling, about $310,000 at current exchange rates, would be considered. Carpets and curtains are negotiable, they say.

Photographs of the rooms taken before the press ban show the Thatcher teakettle still on the stove, as sort of a symbol of a prime minister who still is said to prepare breakfast for her husband. And the toilet seat, the Daily Mirror tabloid (the only paper still pursuing the story) informs its readers, has a fluffy blue cover. "Tory blue, of course," they report, a reference to the Conservative Party colors.

There is no grass for the would-be owner to cut, only a small paved front patio to sweep. The house is only a few yards off Kings Road, a busy boulevard that is home to expensive boutiques and Britain's spike-haired punks, and is undoubtedly more trendy now than it was when the Thatchers first moved in.

The little boxes with the red buttons -- to call security in an emergency -- in the master bedroom wall just above the headboard of the twin beds apparently will be removed if the new owner doesn't want a reminder that Britain's first woman prime minister, the one who has come to be known as the "Iron Lady," slept there.

"A couple of offers" are said to be under consideration at this time, according to agents from other firms, including one described as an Arab buyer by the Mirror. Agents also say they understand that one offer for 250,000 pounds has been turned down.

The Thatchers moved into the 1930s vintage, four-bedroom Chelsea house soon after they were married in 1951. It was there that their twin children grew up. Their son Mark now lives in the United States and their daughter Carol has a place of her own in London.

Since the election, the house had been used as something of a retreat for the family and as a place for reunions with the children. But it has not been used for about a year, and there have been reports that the family had tried, unsuccessfully, to sell the place on its own.

Despite her political power, Thatcher has never seemed to need or be much concerned about expensive surroundings, and the house, according to those who have been inside recently or know the street, is described as "tired" or "well-used." Although recently redecorated, it doesn't have the modern kitchen that some buyers may want.

Agents say other houses of the same kind on the same block, but which have been modernized, go for more than 300,000 pounds and that virtually any house at such a convenient location would be in the 250,000-pound category.

"People who are looking probably do not particularly want to live in the prime minister's house," said one agent. "It adds some to the interest, but not to the value. You would normally expect to get that price in that location."

With the Flood Street house on the market, the only place to get away from Downing Street now is at Chequers, the official country retreat in Kent, southeast of London, that all prime ministers seem to make good use of.

Whether the Thatchers will buy another house in London after the Flood Street sale is not clear, although it has also been reported that they are looking. Soon after moving into Number 10 and making clear at the time that she was not going to sell or rent the Flood Street house, Thatcher said: "If you get in by a democratic system, a day may come when you are turned out by it." And she was determined, she continued, "never, never to put myself in a position of being turned out . . . without a toehold of one's own to which one could retreat."