London — When his four children were young, Antony G. A. Fisher had a chessboard with weighted chessmen laid out on the bottom of the swimming pool at his home in Sussex, England.
''You see,'' his wife, Dorian, explains, ''Antony doesn't like to think of people having nothing to do!''
Mr. Fisher laughs on recalling his symbolic gesture. ''I think the only people to play there,'' he says, ''were Ralph Harris and his son.''
Ralph now is Lord Harris of High Cross. Prime Minister Margaret Thatcher awarded him a life peerage for his 26 years as general director of Britain's influential, and to some controversial, Institute of Economic Affairs (IEA). But it was Mr. Fisher who founded the institute in 1955.
Since then Mr. Fisher has founded three other economic research institutes and helped others to set up 17 more in 14 countries around the world.
Tall, slim, unassuming, but highly articulate, Fisher is a passionate free-market, free-enterprise man.
The research institutes he has helped establish, although strictly academic in nature, look for what might be called ''the freedom alternatives.'' They seek to discover why well-intentioned government policies so often fail and to find alternatives that would fulfill the aims of those policies while maintaining freedom of choice for individuals.
The ground rules Fisher laid down for Britain's IEA hold good for all the institutes: ''Be as objective as possible. Use academic analysis. Always provide answers. Make no attacks on anybody. . . .''
Finally, he insists an institute should remain independent of government, political parties, and any special business interests.
Fisher means to have a good shot at changing world opinion on the supposed benefits of government intervention. And his ground rules may account for the increasing success the new institutions are having and for their increasing numbers. Fisher expects there will be 50 of them in 24 countries by 1987.
Four are influential in the United States: the Manhattan Institute for Policy Research in New York; the National Center for Policy Analysis in Dallas; and the Pacific Institute and the Atlas Research Foundation in San Francisco, where Antony and Dorian Fisher now live.
In Britain, the new Adam Smith Institute has been extremely active. Some of its authors have been called in by government to discuss the future of Europe's Common Agricultural Policy, which is close to disaster.
Antony Fisher stays in the background, advising and raising funds through his Atlas Foundation. He is almost totally unknown to the general public.
''He is a catalyst,'' says his daughter, Linda Whetstone. ''He likes to see others succeed.''
Mrs. Whetstone herself is at once farmer, economist, researcher, writer, and mother of three. The lesson of the swimming pool chess set clearly sank in.
Many people distrust the free-market philosophy. They want governments to cut down unemployment, cut out poverty, provide better welfare and more jobs. Fisher supports these aims, but would pursue them in a different manner than many governments.
''Every economy that has been successful,'' he avers, ''has been successful because of a free market.''
Government controls and high spending never solve problems, he says. But they may set up the very forces that can wreck society, and even lead to war.
In World War II, Fisher was a fighter pilot in the Battle of Britain. His brother Basil, serving in the same squadron, was killed.
And Antony made a frightening discovery about himself - he couldn't shoot. Nobody had taught him how. Antony got out his Mecanno building set and invented a deflection shooting device that the Royal Air Force instantly adopted. (He was awarded the Air Force Cross.)
After the war, the increasing reliance on government also scared him. He read a condensation of Friedrich Hayek's seminal ''Road to Serfdom.'' He sought out Hayek and asked what he, Antony Fisher, could do to avert the dangers both thought they saw ahead.
Hayek replied: ''Change the minds of the molders of opinion. Convince academics, teachers, writers.''
It took seven years for Fisher to begin carrying out this advice. He turned to farming. His cows were wiped out by hoof-and-mouth disease. He started a chicken farm that, without government help, was a big success.
As soon as he was making a profit, he persuaded Ralph Harris to leave a job on a Glasgow newspaper and risk coming to London at (STR)10 a week (then $30) to work part-time in a (STR)3-a-week part-office getting the Institute of Economic Affairs off the ground.
To begin with, he says, ''The IEA was a bit of a joke.'' Not so today. Mrs. Thatcher credits it with ''rebuilding the philosophy'' that made the Conservative Party successful in the past. Britain's new Social Democratic Party has been influenced by its case for free markets.
Even former Labour Prime Minister James Callaghan once agreed in public that the idea that a government can simply spend its way out of a recession is nonsense. Antony Fisher was delighted.
When I called at the Fishers' new pied-a-terre in London recently, the man who doesn't like to think of people having nothing to do was at an easel painting a landscape to hang over their Adam fireplace. I said I had no idea Antony Fisher was also an accomplished artist.
''I'll tell you another thing about him,'' Dorian said. ''He will never sign his paintings!''
She insists he put his initials on this one - and on two others he is painting for the apartment.