For several years now, Margaret Thatcher's husband Denis has had to endure a hilarious biweekly spoof in the satirical magazine Private Eye that purports to be letters from the perennially tipsy prime ministerial consort to his friend, known only as Bill. Here is a bit from the latest entry coinciding with the last days of Britain's national election campaign:

"Dear Bill, only another week, thank God. My hand is already calloused and misshapen from pressing the proletarian flesh and Dr. O'Gooley had to pop in the other day to give me an antilockjaw injection after three weeks of solid grinning. Then last night I woke up shouting 'Hear, hear' in response to Margaret's snores, which will give you some idea how far things have gone . . ."

A play based on the missives called "Anyone for Denis" enjoyed a successful run in London's West End and was shown on television last December in the peak of Christmas viewing season. Several collections of the letters have been published and become bestsellers. And on the night Prime Minister Thatcher announced the upcoming election, "Denis" in the person of his creator and impersonator, John Wells, was extensively interviewed in an otherwise strait-laced late-evening BBC newscast.

On this occasion, "Denis" was, as always, torn between his passion for golf and his devotion to "a tincture," sometimes known as a snifter, but rarely called its rightful name--a drink.

Against that background, coming upon the real Denis Thatcher as he campaigns around the country with his wife represents something of a problem. That is especially the case when he is encountered, as he was the other afternoon at Edinburgh's Caledonian Hotel, hard by the bar in a lounge set aside for the press, imbibing an early gin and tonic and discussing in extensive detail the golfing arrangements in Spain.

It is extremely hard to separate him from the caricature--a fact of which Thatcher is said to be aware and that causes him considerable annoyance.

A tall, lean, bespectacled man, now 68, Thatcher had a successful business career while his wife worked her way up the political ladder. Some of his dealings since living at 10 Downing Street have raised eyebrows, according to an account published by the London Observer last week. In 1980 it developed that a firm of which he was chairman, Chipman Ltd., was making a weed killer containing 2,4,5-t, known as Agent Orange, used with devastating effects during the Vietnam War.

Later that year it was disclosed that Burmah Oil, another company Thatcher was connected with, was paying what the Observer called "starvation wages" to its black workers in South Africa. And in 1981, Thatcher wrote a note on Downing Street stationery urging one of his wife's ministers to speed up a planning appeal for one of his chums.

Thatcher apparently makes no apologies for such matters and makes no secret either of his far right-wing views. Complaining about broadcast coverage of police handling of inner-city riots in 1981, Thatcher reportedly said, "I'll tell you why. It's because our television people are a lot of pinkos and Marxists. A year later, the BBC's chairman said to Thatcher after sitting next to him one evening, "You're so far to the right, you're barely visible!" Significantly, the Observer notes, this anecdote is freely told by Thatcher.

Unlike Britain's other consort, Prince Philip, husband of Queen Elizabeth, Denis Thatcher is not deployed on an official schedule of his own. But he does travel extensively with the prime minister on the hustings, walking behind her and trying for all his might to look interested in a detailed explanation of how thermostat parts are made or what goes on in an automated bakery.

He goes through this ordeal, from all accounts, because he is his wife's greatest fan. Like his fictional counterpart, Denis Thatcher cheerily calls the prime minister "boss" and tells those who ask that she is "one of the most brilliant brains in the country." When Margaret Thatcher gets a standing ovation for a speech, almost the first person up is husband Denis.

The rest of the immediate Thatcher clan consists of the twins, Mark and Carol, now 38. Mark is an accountant with an interest in auto racing and a penchant for appearing in Japanese advertisements that trade on his well-known name. Carol is a journalist who returned from Australia last year to make her way in London. For several months she was the host of a late Saturday night call-in show on commercial radio.

For the campaign, she has taken a leave of absence from her new job as a feature writer on the London Daily Telegraph, to accompany her parents--sort of. She also signed a contract for a book-length personal diary of the campaign and so spends part of her time being swept along in the official entourage, sitting centrally on all the daises, carrying bouquets that get tendered to her mother. The rest of the time, sunglasses perched jauntily on top of her head, she is busily taking notes along with the other traveling scribes.

Asked why she didn't continue her research by joining her mother for the quick trip to last week's Williamsburg summit Carol Thatcher airily replied, "That's not my idea of how to spend a holiday."