One of the glories of the Christmas season in London is the traditional holiday "pantomime," a stage production that is not a pantomime at all but a noisy, glitzy musical extravaganza designed for children of all ages.

No "panto" is more popular than the one built around Dick Whittington, a poor country boy who made his way to London around 1390. As the story is told onstage, Dick (along with his cat) runs into a series of reverses, decides dejectedly to return home--but at the last moment is called back by the bells of London's churches.

"Turn again, Whittington," the bells ring out, "Lord Mayor of London." Sure enough, Dick turns back, becomes a fabulously successful merchant and eventually wins election to the august post of lord mayor.

This season, for the first time in centuries, the people of London have a genuine mayoral melodrama worthy of Dick Whittington. Voters are scheduled to elect London's first citywide mayor in May. Already the campaign has turned into theater, with a list of candidates that can match the characters of any panto in town.

Among those who have entered the race are:

* A self-styled "family man" who complains that he can't get a divorce even though he recently moved in with his fifth mistress.

* A bestselling mystery novelist who got caught encouraging an associate to spin out another fictional tale--under oath in a courtroom.

* A glamorous movie star who finds herself trailing in the polls behind a thoroughly unglamorous pair known as "Dobbo" and "Red Ken."

There's also a graduate of the University of Illinois in the race who seems to have more gravitas than the others. Naturally, she gets far less coverage in the city's 11 daily newspapers.

One reason the race for mayor has been so entertaining is that the hopefuls are campaigning for a completely new job.

Although London is the political, financial and cultural center of Britain, it does not function as a single city. Rather, it is what the British call a conurbation of 33 wards, boroughs and cities, each with a governing board. One of these jurisdictions, covering just a square mile, is the so-called City of London--London's equivalent of Wall Street. It's the financial capital of Europe, but it's just a small corner of London.

Each of the 33 jurisdictions has a lord mayor, but the post is ceremonial. The absence of central authority has made London a nightmare to govern. Over time, Britain's national government has taken over most local power. The District of Columbia has more home rule than London.

But Prime Minister Tony Blair has been pushing plans to return local authority to various segments of the country. Under the process known here as devolution, Blair has created new home rule governments in Scotland, Wales and Northern Ireland. The next stop on the devolution train is London, which is to have a citywide council and a mayor with real power.

Since the mayor of the nation's dominant city will be one of the most visible politicians in Britain, each of the three major parties is putting considerable ingenuity, effort and money into the race. The spending limit for the race is $1.7 million per candidate. That's an astronomical figure in British politics, where candidates for Parliament cannot spend more than $15,000 for a whole campaign.

Blair's Labor Party enjoys strong backing among London voters, and by rights Labor ought to win any citywide election. In fact, one Labor candidate for mayor, Ken Livingstone, consistently leads in opinion polls.

But Blair makes no secret of the fact that he can't stand Livingstone. As his nickname ("Red Ken") suggests, Livingstone is an old-fashioned leftist, eager to expand government services and help redistribute wealth. Blair, a determined centrist, has spent his life fighting the left wing of his own party, and he's hardly pleased at the notion that a famous left-winger could grab such a prestigious new job.

To block Livingstone, Blair has recruited moderate Labor Party figures for the race. A few months ago, he seemed to be backing Glenda Jackson, the Oscar-winning actress who is now a Labor Party stalwart and a member of the House of Commons. But Jackson's campaign never really took off. Today Blair appears to support Frank Dobson, known as "Dobbo," a veteran politician with a Santa Claus-style white beard.

Unfortunately for the prime minister, Jackson and Dobson threaten to split the vote of Labor Party centrists, while Livingstone remains the popular favorite. With the Labor candidate due to be chosen next month, Blair faces a ticklish decision. The prime minister probably can block Livingstone's nomination, but if he does, he will infuriate the rank and file of his own party.

However difficult the Labor Party's candidate selection has been, things have been far worse for the the leading opposition party, the Conservatives.

The Conservatives initially nominated one of their best-known figures: the multimillionaire novelist Jeffrey Archer, whose financial benevolence toward the party over the years won him an appointment to the House of Lords.

In picking Archer, the Tories overlooked the fact that he had a history more colorful than most of the characters in his thrillers. The newspapers here have always treated Archer as a charming rogue. In a typical description, the Guardian described him as "politician, novelist, businessman, and compulsive liar."

Archer has repeatedly battled charges of unethical business dealings and salacious love affairs. In 1987, he won a million-dollar libel suit against a London tabloid that reported that he had had a dalliance with a well-known London prostitute.

All that seemed to be behind him this fall. Archer won the backing of the Conservatives' nominating committee and launched a full-scale campaign. He had barely opened his headquarters, though, when the roof fell in. An old Archer associate, Ted Francis, reportedly angry because Archer had insulted him at a cocktail party, produced tapes of telephone calls in which Archer asked him to lie on the witness stand at the 1987 libel trial.

The charge of suborning perjury is one of the milder accusations that have been thrown at Archer. Nevertheless, the candidate seemed shocked when his old friend turned against him. Rather than fight back, Archer fled London for his country mansion and resigned the nomination.

Even with Archer out of the way, the Conservatives were not out of the woods. The current front-runner for the Tory nomination is a former cabinet member, Steven Norris. He, too, has a history that would fit between the covers of a dime novel.

Married to the same woman for a quarter-century, Norris has had a string of mistresses. He admits to five, but the tabloids suggest there were more. Norris is currently raising the child born to his latest mistress and has not tried to hide the situation from the media.

When reporters recently questioned his romantic entanglements, Norris complained that he would like to marry his current paramour but can't because he cannot afford the divorce settlement his wife is seeking.

Still, Norris is the best known of the Tories running for mayor. He has won the backing of the party's national leader, William Hague, and seems likely to be anointed as the Conservatives' official nominee later this month.

With all the melodrama surrounding the Labor and Conservative candidates, nobody has paid much attention to a quiet, serious, scandal-free candidate named Susan Kramer. She's the nominee of the Liberal Democrats, Britain's third-largest party.

Kramer is married to an American. She has an MBA from the University of Illinois, and spent years as a banker in Chicago. Now back home in London, she has waged an issue-oriented campaign for the mayoralty. But she can't get a drop of ink in the British press.

"I just keep talking about the issues, and that's clearly not the best way to get attention in this race," Kramer said. "The press and the politicians have apparently decided that the real reason we're having an election for mayor of London is to keep the people entertained."

CAPTION: From top, novelist Jeffrey Archer, actress Glenda Jackson and leftist Ken Livingstone.