LONDON — FOR the first time since she was elected leader of Britain's Conservative Party 14 years ago, Margaret Thatcher is to be challenged for the post. Sir Anthony Meyer, a backbench member of Parliament (MP) and long-standing critic of the prime minister's policies, has said he intends to contest the leadership of his own party to underline ``growing discontent with her policies and leadership style.''
The ballot among Tory MPs is expected within three weeks.
There are 374 Tory MPs in the Commons. If between 50 and 100 ``defected,'' either by voting against or abstaining, in aparty leadership ballot, this would be interpreted as a major setback for Thatcher.
Meanwhile, the Tories have received their lowest popularity rating in nine years. The Sunday Times published an opinion poll that showed the opposition Labour Party with 51 percent support, 14 points ahead of the Conservatives. It was Labour's biggest lead since 1980. In a poll in the Observer on Sunday, two thirds of voters polled said Thatcher should stand down before the next general election, which must be called by mid-1992.
Sir Anthony sees himself not as a serious contender for the Tory leadership, but as a stalking horse for ``widespread unhappiness'' with Thatcher and her policies. He says he would be prepared to step aside if a ``more senior and better qualified candidate'' was prepared to challenge the prime minister.
Sir Anthony's decision to throw his hat into the ring follows a crisis in the Conservative Party sparked off by the resignation of Nigel Lawson as chancellor of the exchequer. Critics charged that Thatcher acted in a high-handed manner and lacked sympathy for the European Community.
Sir Anthony reflects the belief of a number of Conservative MPs that the government's strict cash controls on social security and its determination to reform the socialized health service are unpopular with many voters.
The leadership contest will coincide with a unique phase in British politics introduced by the televising of House of Commons proceedings that began on Nov. 21. From now on, twice a week during questions to the prime minister, Thatcher will be seen for the first time by millions of viewers having to defend her policies against opposition attack.
In the first televised debate from the House of Commons on Nov. 21, the Labour leader, Neil Kinnock, was widely credited with having performed effectively. One of his officials said afterward that Mr. Kinnock would carry the attack to the prime minister now that her position in her own party as ``under open threat.''
In theory, the leadership of the Conservatives is decided every year, but until now nobody has challenged Thatcher, who has been prime minister since 1979 and was leader of her party for four years before that.
After the opening televised session of the Commons, a Labour backbencher said, ``Mr. Kinnock came through as a warm, sincere speaker, with lots of humor.''
Thatcher, who appeared less relaxed, was defended by a Downing Street official: ``She did not try to play to the gallery. She behaved as she always does - with dignity,'' the official said.
The arrival of TV in the House of Commons was preceded two years ago by the first televised broadcasts of the unelected House of Lords. Even now the Commons are admitting the cameras for only a six-month trial. Already, however, it seems improbable that the cameras will ever be removed.
Bernard Weatherill, speaker of the Commons, normally the most somber of men, has described it as ``the best show in town.'' One critic forecast that he would become a media star in his own right, in his full white wig and black cloak and garters.
More than a dozen times in the opening televised session, Mr. Speaker rose magisterially before the cameras to admonish MPs with the words ``order, order,'' spoken in a powerful baritone voice.
In the House of Commons, which is essentially an arena, Thatcher uses different methods, often trying to shout her opponents down.
A Labour Party media adviser said: ``If she tries to use that technique in future, she will be accused of behaving like a strident fishwife. Viewers will not find that an attractive quality.''