The Shrapnel Academy<i> by Fay Weldon (Viking: $15.95; 186 pp.) </i>

This is an explosive little novel, to English drawing room comedy what the Hindenburg was to zeppelin flight.

Shrapnel Academy, a well-endowed mythic military school named after the man who invented the exploding cannonball, gathers a sort of numskulls’ Noah’s Ark for the annual Eve-of-Waterloo dinner: Gen. Leo Makeshift, oafish but agreeable, will deliver the Wellington lecture; Bella Morthampton, his secretary in title but his mistress in fact, will devour the tough caribou patties from a 1794 Canadian recipe; Mew Whittaker will be mistaken for a Times of London correspondent when, in reality, she represents the ferociously feminist Women’s Times. Fold in, among others, an idiot savant who makes his living selling deadly weapons, an overage secret agent, a dithering married couple and two frightened faculty members--a human sampler of the old Empire in accelerated decline.

Imagine Alastair Sim, Joyce Grenfell, Joan Greenwood, Ian Carmichael, Terry-Thomas and Sir Alec Guinness at one table; discover they have hidden alliances and watch them savage each other.

Joan Lumb runs this foolish academy, a lady with an exquisite sense of putting people in place and putting classes in descending orders of status. “So important,” according to Lumb, “to get the seating arrangements right. A dinner party’s like a cocktail--no matter how good the ingredients, if you don’t stir properly, everything’s wasted.” Male, white managers are at the top of her social hierarchy; male, black managers rank ahead of female, white servants in the middle; female, black servants are at the bottom.

And at the literal bottom of the academy are uncounted hundreds of servants of all colors--plus their spouses, friends and fellow runaways from Nicaragua, Sri Lanka, Cuba, Soweto--all those impolite places where bigotry or battle make life dangerous. Lumb, like any colonial officer, doesn’t know what malice lurks among the lower lives. She doesn’t even have a census of the oppressed population.

Upstairs, the relics clutching to title and tiara. Downstairs, the refugees holding to life and limb. Boom.

That doesn’t seem so funny, does it? More like a Marxist struggle knotted in old school ties? Well, Fay Weldon isn’t any kinder to the huddled masses than the gross gourmands. She caricatures the grotesqueries of polite and impolite society, drums up a murderous little conflict within the building and uses the absurd academy as a microcosm for making a bloody mockery of all wars. Before she has finished clearing the banquet table: A servant has died in childbirth--from inattention; a dog has been slaughtered and served to the guests--as a mousse in finger sandwiches--and a nuclear explosion levels both class distinctions and the structure.

If that still doesn’t seem so funny, Weldon interlards her story with asides to the reader and scraps of narrative from historic battles. Little shards, like shrapnel itself, can be devastating: “Peace may look good to governments,” says the satiric authorial voice, “but it is only the quiet time an army needs to recover from the last war and prepare for the next. . . . Peace is good for agriculture, but bad for the economy, bad for love and bad for civilian morale. Civil unrest, blasphemy, discontent and crime flourish in times of peace.”

Other scraps seem merely precious: “Gentle Reader! What have I said! You are no more gentle than I am. I apologize for insulting you. You are as ferocious as anyone else. The notion that the reader is gentle is very bad for both readers and writers, and the latter do tend to encourage the former in this belief.” If readers were indeed gentle, goes the logic, then we wouldn’t be blowing each other to smithereens.

Fay Weldon has worked her way through feminism and fantasy and plain fatness in nearly one dozen earlier novels. She has written for the stage and the screen. She carries a long, shiny needle, the better to puncture what passes for acceptable behavior. Here, as before, she knows the fatuity of people in highest places: “It is hard to imagine how barbarous the language of our leaders is, in private, how simple and emotive their judgments, how their love of money and power and vengeance rises to the surface like the white crust on boiling strawberry jam.”

The cruelty also rises. Truly gentle readers may be appalled at the gore and violence flying around this farce. Truly cynical readers may be delighted by a comedy of manners in which everyone’s manners are most atrocious. This reader was sometimes appalled, often amused--and generally disconcerted by the asides, wondering whether they were designed as playfulness, punctuation or simple padding. A belly laugh for strong stomachs.