Cambridge, England — A prosperous young farmer in the middle of England was watching the 9 o'clock BBC television news one night last May. When the face of a starving child in Ethiopia flashed onto the screen, he turned back to a magazine on his lap: He had never liked looking at such heart-rending scenes.
A few seconds later he heard the word ''grain'' and it launched him out of his chair and into action.
Vigorous, sandy-haired Oliver Walston farms 3,000 acres of rich soil at Thriplow near Cambridge.
Last year he grew 3,500 tons of grain - enough to make 5 million loaves of bread. By last May, in common with grain farmers all over Britain and the rest of Europe, he knew the l984 harvest would be even better (which it was: an all-time record).
Yet much of his grain was destined for already-huge government stocks, part of a 10-nation European Community wheat ''mountain'' that, by July 31, 1984, stood at 3.5 million tons.
So he sat down at a computer and tapped out a six-point plan, complete with title, ''Send A Tonne To Africa.''
His idea: Farmers agree to sell their grain in the normal way to a grain buyer, adding simply, ''and send a tonne to Africa.''
The grain merchant deducts from the payment the price of one ton of wheat - just over (STR)100 ($120) - and sends it to a bank in Cambridge, England. If the funds reach (STR)1 million ($1.2 million), Mr. Walston will buy 10,000 tons of wheat on the open market and ship it to Port Sudan.
Why not direct to Ethiopia? The only relief agency interested in handling his grain at first was War on Want, of Britain, which sends food through Port Sudan for guerrillas in Eritrea. By October the first (STR)100,000 had come in.
Walston at once bought 1,000 tons and sent it to Port Sudan on a ship leaving the port of Hull in October with other wheat on board.
In early November he turned up in the lobby of a hotel in Addis Ababa. He had just flown in on a Boeing 707 chartered by a group of British businessmen with 32 tons of his ''Save a Tonne'' wheat. He was enthusiastic about his next moves: back to London the next day then a long return flight a few days later to Khartoum and a journey into Ethiopian rebel territory via Port Sudan. He said he had already raised (STR)350,000 ($420,000) and was well on target for (STR)1 million ($1.2 million) for Christmas.
His idea delights many but offends some.
''Excuse the cynicism,'' said the headline over an editorial in Farming News, a British publication. Editor Marcus Oliver said the campaign ''smacks of self-interest'' as an effort to bolster the image of big farmers.
''I approve of helping the hungry,'' Mr. Oliver said in an interview. ''One doesn't want to appear Micawber-ish, but such projects should be looked at more thoroughly.''
Andrew Arbuckle, who farms 350 acres in Fife in Scotland, has economic reservations. He sent only half a ton to Africa because he earns only 10 percent of his income from grain. The rest comes from potatoes, strawberries, and blackberries, which currently fetch low prices.
Walston, meanwhile, is trying to widen his idea through the American Farm Bureau Federation.
Speeding around his farm in a blue Mercedes jeep, and then over a lunch of borscht and brown bread in his kitchen, he says: ''I've never raised money for charity before, but today, for the first time since the Middle Ages, Britain has so much surplus grain that it is a grain exporter.
''Yes,'' he adds, ''it would be best to send money to Ethiopia, but farmers are more generous if it is their own wheat going out there.
''And yes, War on Want feeds northern secessionists (fighting the Ethiopian government), but they are hungry people too. . . .''
War on Want spokeswoman Sarah Mitchell says her organization had ''at least'' 110 trucks ready at Port Sudan. Several Western aid officials were skeptical that they could be kept in good repair.
''Look,'' Oliver Walston says, ''whenever I give talks there's always someone in the back of the hall who stands up and says, 'People are starving, and what are you doing about it?'
''I'm not kidding myself that 10,000 tons will make all that much difference.
''But at least we're doing something. . . .