Interview: David McCallum, actor

In a recent episode of Mad Men, a show renowned for its verisimilitude, we see ten-year-old Sally Draper transfixed – practically hypnotised – by an image on the television. When the camera cuts to the small screen, it's a lingering close-up of Russian agent Illya Kuryakin, in The Man from U.N.C.L.E..

• McCallum with his wife, Katherine Carpenter Picture: Getty

That "Russian" was actually born in Glasgow, in 1933. With his blond Beatle bob and striking features, actor David McCallum became a heart-throb who inspired frenzy among his fans. Thousands of letters from love-struck viewers poured into the studio every week, and he was mobbed when he ventured out.

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Since joining Actor's Equity in 1946, McCallum has worked virtually non-stop, but thanks to the popular American television show NCIS, about Navy crime fighters, he's won a fresh legion of swooning fans, tuning in to see him play pathologist "Ducky" Mallard. Now they'll have a chance to catch up on the award-winning BBC drama Colditz, which originally ran from 1972-4, when the Yesterday channel reprises the 28-part series. It will kick off with a documentary taking a fresh look at the legendary prisoner of war camp.

Maybe it's because his lilting voice is so familiar, or because he's so instantly friendly, but talking to McCallum feels as cosy as slipping into a warm bath. This, despite never having met, and a noisy connection to Manhattan, where he's based. Or maybe it's the connection to home, for I quickly discover that you can take the man out of Scotland, but not the Scotland out of the man.

He is the second son of Dorothy Dorman, a cellist, and David McCallum, Sr, an orchestra leader who headed up the London Philharmonic. "I was born by the Botanic Gardens, but 65 Clouston Street is where my grandfather lived, and most of the time I'd stay there. Father, way back in the 1930s, was with the Scottish Orchestra, and so he would be working at the BBC there.

"When I was a kid, late at night we would go and get a bag of bits – which is just fat and flour and salt. We've come to our senses in this family now. I have five little grandchildren, the eldest of whom was just seven, and the youngest is four months, so with five little tow-headed boys, both mothers are acutely aware of health and nutrition. I was lucky, during the war, that my father got all the sugar rations for his tea – he was a tea jenny, as we say in Scotland – so I never developed a sweet tooth."We moved to Hampstead in 1936, when Father became leader of the London Philharmonic. At the end of 1939 or the beginning of 1940, I was evacuated. I always seem to think it was with one of the little brown boxes with a gas mask and a piece of string and a label tied on my coat, but probably my mother took me up in a more civilised manner. We stayed with her sister, Margaret, for a number of years, then took a house by Loch Lomond, at Gartocharn, called Rose Cottage."

He jokes about his Calvinist upbringing, but remembers his childhood fondly, despite the privations of war. "(I remember] my mother inventing a dish where you took potatoes and mashed them, and grated carrots, and we had two ounces of cheese for a week or something, so you grated a little bit of that on top with a little salt and pepper, and baked it in the oven until it had a crisp top. We called it 'Lord Walton', who was the Minister for Food."

Music was omnipresent, and his parents assumed he'd follow them into the family business. Did he realise how famous his father was, or simply assume that's what all fathers were like? "Father was unique in that his hands were really the centre of his life, and keeping his hands safe and in perfect condition was paramount. I've never said that to anyone before, but that is the way that I remember him. He would practise his violin incessantly, so we had the sound of the music throughout the house all the time.

"As a child I would go with him down to the studios where Jascha Heifetz was recording Brahms. I remember Heifetz's G string broke while playing a cadenza, and he handed it to me. And conductor Thomas Beecham, when he was recording The Damnation of Faust, which has that wonderful opening, ending in a huge crescendo. He stopped the whole orchestra and turned to me in the front row, all alone in this huge place, and whispered: 'Let's do it again!'"

McCallum's father polled friends about which instrument his son should study, with a view to future employment opportunities, and settled on the oboe. "Here am I six or seven years old, and he's choosing my profession," McCallum recalls, with a tender chuckle that speaks to what a close-knit family they must have been. He still plays that oboe, but music never grabbed him the way acting did. "I played The Little Prince in Shakespeare's King John, at one of those local things where people do skits and songs. Mine was the little prince having his eyes put out by this terrible man, and I acted it, evidently, very well, because I got a standing ovation. I wasn't more than eight.

"And I said: 'Hey, hey, hey, this is kinda cool!' I don't know if I consciously thought it, but I had found the place I wanted to be: on a stage, with the lights and make-up and the people. I'm exactly the same to this day; the feeling has never left."

Studying at RADA, he was as keen to absorb the mechanics of mounting a production as he was the acting skills, and for years he juggled the two, often functioning as stage manager while also appearing in a show. He was discovered, legend has it, when a photo of McCallum resembling James Dean caught the attention of the Rank Organisation, who signed him in 1957.

That same year he married Jill Ireland, with whom he had two sons and a daughter. They moved to California in the early 1960s when he was cast as Judas Iscariot, in The Greatest Story Ever Told. When that marriage broke up he found love again with Katherine Carpenter. They married in 1967, and have a son and a daughter, all of whom live in New York, though McCallum spends months of every year filming NCIS on the West Coast.

He's famed for his thorough research, and took such an interest in the role of Dr Mallard that he trained with the Los Angeles Chief Pathologist, and can now perform autopsies himself. And all those years ago, he recalls, he prepared for Colditz by drawing on his military experience doing his National Service in West Africa, and by visiting the former prisoner of war camp.

"I am known for being somewhat obsessive, but I felt it important to go to Leipzig. When we got there, Colditz was basically used as a mental hospital, so there was a somewhat Fellini-esque element to the whole thing. It was a long project, and it was nice to be with (co-star] Bob Wagner. He's a lovely man, and recently guest-starred on NCIS. Colditz was a very timely, great story – and it was also regular employment for a couple of years, which is always good for an actor."

Wagner's not the only Hollywood legend McCallum has shared the spotlight with. He appeared in John Huston's Freud, with Montgomery Clift, who became a friend and in Peter Ustinov's Billy Budd. He also had a small role in A Night to Remember, starring Kenneth More. "Back in U.N.C.L.E. Days, everybody from Elsa Lanchester to Joan Crawford and Jack Palance was there (as a guest star], and George Sanders came back a couple of times. Just to meet all those people back then was a thrill."

Was he starstruck by any of them? "All of them!" he laughs. "You know, I grew up going to the local Odeon. If my father went we sat in the two and sixpence upstairs, otherwise it was the one and three downstairs. I grew up watching all these wonderful old black-and-white movies. And then I went to Hollywood to test for The Greatest Story Ever Told, with George Stevens, and met Pat Boone and Roddy McDowall and John Wayne – suddenly you're in among them all. That little boy that went to the Odeon never left me, so it's constantly fascinating."

I'm dying to know what it was like being as popular as the Beatles. He sounds a bit blas and a bit bemused. "There is a practicality about it. You have to deal with it by not going to certain places. I was rescued from Central Park by mounted police once. When I went to Macy's department store the fans did $25,000 worth of damage and they had to close Herald Square to get me out. That's pretty classic, but you just have to deal with it. And then whoever was next came along, and you get dropped overnight, which is a relief.

"But it's all part of a wonderful, crazy life. I was born in Glasgow; I went to school in Gartocharn and at Stewarton School in Stirlingshire – across the hills in muddy boots with my jammy piece in my bag – and then came down to London. The whole thing is a sort of huge collage of a life. It's always been wonderful."

Autopsies aside, what's the craziest thing he's done in the name of research? "Well I wouldn't say crazy, but my study of the last few years has been one of the most exciting things that's ever happened to me. To hold a heart or have it held in front of you, and be shown the actual arteries on the outside, and see how tiny they are and how easy it would be to clog them!

"Also, during The Greatest Story Ever Told there was a helicopter they were using for a camera, so they had no bubble on it, just the seats. Two of us got in with a pilot and he flew us up the Grand Canyon: over the lip, right down to water level, and he flew about two feet off the water right up the canyon. Production were furious, but boy, what a wonderful moment."

You know, I tease, you're a sex symbol all over again, thanks to NCIS. "Oh I hope!" he says. "Anybody who can be a sex symbol in their 70s! I love it!"

• Colditz - The Legend and Colditz the TV series, Yesterday, from Monday, 25 October, at 10pm (Sky 537, Virgin 203, Freeview 12)