LONDON (AP) _ A bespectacled figure in full-bottomed wig and 18th century court dress who intones ''Order, order 3/8'' over a cacophony of cheers and jeers is an unlikely celebrity in modern Britain.

But the speaker of the House of Commons has become one since television cameras entered the Mother of Parliaments 18 months ago.

''I often say I'm not in the entertainment business,'' said Bernard Weatherill, who holds the office created in the 14th century. ''This is a workshop.''

Weatherill has presided over the rumbustious Commons since 1983 with a skillful mixture of schoolmasterly reprimands, jollying-along good humor, widely acclaimed impartiality and occasional revenge.

Hundreds of the 650 members vie to ask questions during the 15-minute prime minister's question time on Tuesdays and Thursdays. It is the one bit of parliamentary theater always carried live on television and seen across the Atlantic on C-Span.

The speaker decides who is chosen - ''called,'' in Commons parlance - from among the rank-and-file legislators who spring up from the green leather benches signaling for his favor.

''After all, if people mess around, I don't have to call them,'' Weatherill said with a chuckle. ''I don't see them.''

Weatherill, 70, has been a Conservative Party legislator since 1964. Commons members elected him speaker in 1983.

In the grand apartments in the Palace of Westminster that go with the $95,500-a-year job, Weatherill conducted the interview in a palatial study, surrounded by portraits of speakers from past centuries.

His unchanging uniform adds to the air of timelessness and tradition.

Weatherill is steeped in it. He sprinkles anecdotes with quotes from historians, from past speakers, from Winston Churchill, from a vicar who wrote to complain about members shouting at each other, from American viewers who write in at the rate of 20 a week - ''nearly all admiring.''

He presides at a difficult time.

The opposition Labor Party has become increasingly frustrated by three successive general election defeats and is seldom able to block a Conservative prime minister.

There was a risk of the opposition abandoning the Commons, particularly in 1987 when Prime Minister Margaret Thatcher won her third successive election, Weatherill said.

''They said, 'What's the point of coming here? The government's going to win the vote every night.' I'd say to them, 'I know that. ... What matters here is winning the argument.'''

To prove that, Weatherill keeps a list of legislators he says have swayed the Commons with a single speech.

At least one made history. A devastating attack by former Foreign Secretary Sir Geoffrey Howe precipitated the Conservative Party revolt that brought down Mrs. Thatcher in November.

Howe accused the prime minister he had served for more than a decade of undermining British interests in Europe.

''The time has come for others to consider their response to the tragic conflict of loyalty with which I have myself wrestled for perhaps too long,'' he told the packed and silent chamber.

''Here you saw effectively a bloodless coup,'' Weatherill recalled. ''It was a great parliamentary occasion none of us will ever, ever forget.''

Also on the list is Tony Benn, doyen of the Labor left, whose impassioned speech in 1987 swung the Commons against a government attempt to block a private viewing of a banned TV documentary.

In a system that makes a prime minister with a big majority in Parliament nearly unstoppable, Weatherill has made sure the opposition is heard, ministers are quizzed and that Labor's shrinking left wing has its say.

Such impartiality has earned the disapproval of some in his own party - particularly under Mrs. Thatcher, who had supported another candidate for speaker in 1983.

''It took her own chief whip, John Wakeham, to remind her of constitutional practice, that the speaker is not ... a slave, an echo, a suit of clothes,'' political commentator Edward Pearce wrote in his book on Parliament, ''Hummingbirds and Hyenas.''

Has there been pressure to be a bit more partisan?

''There has been, of course,'' Weatherill said with a laugh. ''The government with a very big majority is susceptible to the old adage that all power is delightful but absolute power is absolutely delightful.''

From Mrs. Thatcher? ''I've always got on extremely well with her ... but I think she accepts I'm my own man and not prepared to be persuaded or browbeaten.''

His believes his major achievement has been ''to ensure that the democratic parliamentary system operated fairly ... when the government had a very large majority.''

Weatherill is not bothered by the robust exchanges in the Commons, where government legislators sit on one side of the chamber and their opponents on the other.

There are groans, giggling and shouts of ''Rubbish 3/8'' There also are concerted attempts to disrupt speeches, and lawmakers sometimes drown out the prime minister and Cabinet members.

''Our parliamentary system is not and never has been consensus politics,'' Weatherill said. ''It is specifically adversersial politics. ... I'm a sort of lightning conductor.''

Weatherill will retire at the next election, later this year or next. What will he miss most?

''Do you really want to know? A driver.''