Come campaign time, English master art of oddball politics. Eccentricity has a field day on political fringes

Whack-a-do, whack-a-do, whack-a-do. Music fades. Voice, BBCish, in tones sotto voce ``That was a paid political broadcast by the Official Monster Raving Loony Party.'' The example is, of course, fictitious. But the political party, one of a plethora of parties contesting the June 11 British elections is not.

Not to be outdone in the wacky, Monty Pythonesque world of British politics, P.H. Stephenson of the Blancmange Throwers' Party has hurled her candidacy at the affluent Windsor and Maidenhead constituency. She intends to take on the constituency's sitting Conservative Party member of Parliament - as well as the Labour, Liberal, Green Party, and Independent Conservative candidates.

Prime Minister Margaret Thatcher, in her own constituency of Finchley, also has unexpected opposition from a Lord Buckethead of the Gremloids.

In a country that indulges political eccentricities without apparently ever intending to vote them in, the British voter can find practically every social whim is catered to at the polls.

Unhappy with the so-called establishment parties, the voter could turn to the following diversions, all of which have put forward at least one candidate in the June 11 poll: Bread (the Creek Road Fresh Bread Party), OOBPC (the Only Official Best Party Candidate), OFP (the Official Fidgetitious Party), RABIES (the Rainbow Alliance Brixton Insane Extremist Section), and LAPP (the Let's Have Another Party Party).

The tendency toward crackpot, oddball political affiliations appears to be a peculiarly English phenomenon. In Scotland, Northern Ireland, and Wales no such frivolous affiliations exist. The wellspring of these parties is straight from the world of Monty Python.

Some years back this British television comedy program simulated a TV studio on polling night in which returns from a general election were analyzed. The fight was between the Sensible and the Silly Parties, but challenged by the splinter groups of the Super-Sensible and Super-Silly Parties.

At one moment in the broadcast, a commentator refers to the ``candidacy of Mary Whitehouse, who keeps an eagle eye out for what she thinks are unsuitable programs for evening television viewing and is regarded as unofficial custodian of people's morals on TV. At this point the announcer in a frisson of excitment announces the latest return: ``We have just learned that Mary Whitehouse has taken Umbrage.''

But in the real world of British politics, political humor is not so readily available. What there is is frequently wrapped in political scorn. Mrs. Thatcher, a Conservative who claimed that Labour was deliberately concealing a more radical agenda, referred to the printed Labour manifesto as the ``iceberg'' manifesto. It was an irresistible opportunity for Neil Kinnock, Labour's leader, to dub Mrs. Thatcher ``the Titanic.''

Meanwhile, David Owen, leader of the Social Democratic Party and critical of Labour's defense policies, said he would sooner entrust the country's defense to ``a sandbag, than a windbag.'' Mr. Kinnock, one of Britain's most loquacious politicians, has been nicknamed the ``Welsh windbag.'' Norman Tebbit, Conservative Party chairman, whom critics call ``skinhead'' because he is seen to be tough and abrasive, says that to ask Kinnock for a brief answer to a brief question was like a man trying to get a drink from a burst watermain.

But for a slick, witty campaign message, none of the latter-day politicians has equaled the wit of postwar Welsh Labour Cabinet minister and impressive orator Aneurin (Nye) Bevan who proclaimed ``The kingdom of Bevan is Nye.''