The war intervened, and he wanted to go, but they tested him and they found that the rodeo rider who often slept in a tent was 4F - "They said there were a couple of spots on my lung." So the only thing he did for a while was train horses for the cavalry - the war that ended with the atom bomb still had dreams of cavalry at the outset. But a lot of guys he knew went off and never came back, and it's not a thing he's ever liked to talk about - until David Lynch put a scene in The Straight Story in which he and another old-timer talk about the war. And then, all of a sudden, the guy past 75 found that he could act, just like Montgomery Clift.

In Hollywood in the 1920s and 1930s, real Western veterans rubbed shoulders with the make-believe of the movies. Wyatt Earp died in Los Angeles in 1929, having a year before assisted on a romantic biography of himself. The movie scenarios were far from honest, but a Western code was passed on - all the things Farnsworth had taught Clift. In the late 1940s, John Ford picked out one rider - Ben Johnson, an Oklahoman cowboy - and gave him lines. In 1971, on The Last Picture Show, Johnson won the supporting actor Oscar. He made plenty of big movies, such as Peckinpah's The Wild Bunch, but he always went back to his ranch between chores.

Farnsworth and Johnson were friends. But Farnsworth was more modest and never dreamt of getting lines, of acting, getting his name on a picture. But then in 1968 he was on The Stalking Moon, a Gregory Peck picture, directed by Robert Mulligan and produced by Alan J Pakula. "And I was just riding in it, but they needed a line, and out on location they didn't have anyone. So I read the line, and it was OK, I guess; and then a few years later - like 10 years - Alan Pakula was doing Comes a Horseman, and there was the role of an old-timer who worked for Jane Fonda. And he thought of that cowboy from Stalking Moon. He showed me the script and said "What do you think?" I went home and read it, and I reckoned it was beyond me. It was 10 weeks' work. But my wife read it too, and she said, `We can do this', and she helped me. First day, I did a couple of lines and Pakula said, `That's it. Don't change a thing.' "

He was nominated for a best supporting actor Oscar but lost to Christopher Walken in The Deer Hunter. But people noticed, and he was offered more speaking parts. In Canada, a young director named Phillip Borsos thought of him for the role of Bill Miner in The Grey Fox, the based-on-fact story of a gentle, polite train robber who had a way with the ladies. This was a starring part, and in 1982 The Grey Fox was a sensation.

He did other things - The Natural and The Two Jakes, and the old guy who rescues Alec Baldwin and Kim Basinger in the remake of The Getaway. But he had moved to New Mexico and he was running longhorn cattle on his land, near Lincoln, the town where Billy the Kid killed deputies Bell and Ollinger and went on the run the last time before Pat Garrett nailed him in Fort Sumner. This is rolling prairie land, with mesas, canyon and rivers - gorgeous land.

And Farnsworth didn't much like to fly. He was nervous in a plane. Which may account for his recent engagement to Jewel Van Halin, a Delta Airlines stewardess. He's the sort of moist-eyed old-timer a younger woman can feel for. And he would grin wryly if you put it that way.

You might have thought that his life had had its share of wonders. But then along came David Lynch, who said he had a simple story to film - how a man called how Alvin Straight of Iowa drove on a John Deere lawn tractor to Wisconsin to see his brother one last time. That's all The Straight Story is, that and the people Alvin meets along the way, and how he talks to his daughter, Sissy Spacek, and meets his brother, Harry Dean Stanton.

Farnsworth went to Cannes last spring with this startlingly innocent picture, and got a six-minute ovation. At the Oscars next March, he'll have tough riders to keep up with: Kevin Spacey in American Beauty; Matt Damon in The Talented Mr Ripley; Jim Carrey in Man on the Moon; Denzel Washington in The Hurricane; Russell Crowe in The Insider; Tom Hanks in The Green Mile; Al Pacino in Any Sunday.

With Farnsworth, that's eight strong contenders for Best Actor already, and you could argue that The Straight Story is old-fashioned and simplistic. And so it might have been - without the gravity of Richard Farnsworth. It's as if Montgomery Clift had lived to play old men - or as if Farnsworth had been touched by Clift's greatness in Red River.