From Shakespeare to Sheridan, from Congreve to Shaw, the comic stage here has been distinguished by scintillating playwrights. But none ever enjoyed the commercial success of a knockabout farce by a couple of obscure, contemporary craftsmen, Anthony Marriot and Alastair Foot.

Their triumphant vehicle boasts a brilliant title, "No Sex, Please - We're British," and it is still going strong in its eighth year. Each night, the package bus tours from Birmingham and Brussels, Liverpool and Lyon unload their cargoes for a Naughty but nice little outing at the Strand Theater.

An essentially innocent affair - "There isn't an offensive word in it," boasts John Gale, the shrewd producer - "No Sex, Please" played its 3,000th performance in August. It is now the longest running comedy in British theater history.

More than a year ago, the farce topped the old record of 2,547 set by "There's a Girl in My Soup." Both plays have probably drawn thousands from the provinces who had never before seen live theater.

"NO SEX, PLEASE" exploits a long line of familiar gags. Moyra Fraser is an interfering mother-in-law. Tara Soppet and Graham Wyles are the newly-weds who can't bear to stop clinging. Trousers and pajama bottoms fall. Pretty girls in bras and panties embarrass shy men. A bank executive, Leslie Bromhead, is stuffy. Classic misidentity turns up in the person of Hugh Lloyd, a crusty bank examiner mistaken for a purveyor of pornography.

But this also is a tightly constructed farce that moves at a brisk clip, offers a slight gag a minute, propels its characters in and out of slamming doors like the Marx brothers and has drawn more than 2.5 million people. What they find funny offers some useful clues to the British temper.

The plot is disarmingly simple. A young bride, wife of a suburban bank branch manager, sends off for what she thinks is Swedish glassware and receives a box of pornographic photos. She and her husband frantically try to dispose of the stuff before his mother, boss and a police inspector find out. The couple, however, are deluged with a crescendo of pornographic films, books and more. The climax comes when they are sent a pair of live tarts, a cuddly blond and a stately black. They arrive almost simultaneously with the suspicious bank examiner.

Michael Billington, a thoughtful critic, for The Guardian newspaper, has suggested that all this is a vulgarized form of Ionesco, who wrote one play about an empty room that gradually fills with furniture until all Paris is immobilized and another about a corpse that swells until it destroys an apartment.

"No Sex, Please," said Billington, is simply a common man's version of Ionesco, "man's panic as his attempt to create a decent, orderly world for himself is overtaken by some uncontrollable, ever-multiplying object.

IT IS NOT LIKELY that the authors of "No Sex, Please" have spent much time studying Ionesco, but producer Gale likes the comparison. In his cozy office over the theater, he said:

"Yes, things are overwhelming us in the last few years. This play encapsulates the dilemma of people in an assuring way. That's why audiences associate with it."

They are also ljiawy owy oawyoayo piece of innocent burlesque, now-you-see-it, now-you-don't that is "encapsulated" in the title. Theater goers at the Strand can imagine but never see the pornographic pictures and films. They hear the title but must visualize the contents of "1001 Perversions," the book that is delivered by the carload to the newlyweds. The audience can hear the offstage sounds of the two tarts romping with the drugged bank examiner, but nothing consequential happens on stage. "Farce is about innocence," says Gale. "There is a great amount of maneuvering but your naughty cranks are always foiled."

The three attractive young ladies in underwear who cavort for "No Sex" are suitable for grandma and her 12-year-old granddaughter, especially if they are from out of town.

FOR REASONS THAT no foreigner will ever understand, masses of Britons find the sound of flushing toilets and the sight of bare male buttocks irresistably uproarious. "No Sex, Please" does not disappoint. An offstage toilet is flushed frequently. Both Hugh Lloyd, the bank examiner, and Ian Masters, a superbly comic fall guy, lose their trousers onstage in the course of the evening.

"No Sex, Please" is a professional as well as cynical. Its sight gags - a trouserless Masters literally climbing a wall, the newlyweds pushing mother-in-law, boss and tarts in and out of different rooms - are performed with a brio and timing that Feydeau would have admired.

But the key to "No Sex, Please" is hypocrisy, a trait that the French have always said was the English vice. Before the curtain falls, the stuffy bank boss turns out to have been an old client of the tarts, the stern police inspector leeringly invites the shy bank cashier to a private showing of the seized pornographic films, and the crusty bank examiner is revealed as a regular at the inspector's stag night.

Gale claims his great hit appeals because it is a funny and disapproving comment on the permissive society. More likely, it has grossed more than $6 million because it lures those who are outside of, but privately long, for a glimpse of a more libertarian world.