“I’m utterly devastated. Robert and I worked together for many years, and losing him is like losing a part of me.”

What do you like about playing Ducky?

He’s an extremely enthusiastic individual who is fond of solving problems. I share his enthusiasm for life and his attention to detail — and his intolerance for mediocrity.

Did you know anything about pathology before you took the role?

I knew nothing about it, so there was a bit of a challenge. It’s been 15 years of learning. I’ve been in with the body, watching full autopsies being taught by the pathologist.

What keeps you interested in the show?

What really has sustained me the whole time is the cast. It’s a bit like having a second family. It’s changed radically in the last year since Michael [Weatherly] left, so from the original cast, there’s only Mark [Harmon], Pauley [Perrette] and me.

Is there a special colleague who meant a lot to you in your career?

Montgomery Clift. We did [1962’s] Freud together. He used to come to London, and we’d have dinner. I remember I was driving on Santa Monica Boulevard, and I heard over the radio Monty had died. I pulled over, and I wept. He was an extraordinary creature.

How do you look back on the making of The Great Escape in 1963? It must hold bittersweet memories since it’s where your then-wife, Jill Ireland, began her affair with Charles Bronson.

No, I met Charles on that film, and he became a very close friend. When I went to America for an audition, Charles and Jill continued their affair, which later led to our divorce, and Charles ended up marrying Jill. I’m thankful to Charles for that, because then I found my future wife, Katherine, and we’ve now been married for 52 years.

Did you have a sense that The Man From U.N.C.L.E. would be a sensation?

No, I got a job, and I was able to pay the bills. It was wonderful I had that opportunity. My part was very minor, and it just developed.

MGM said they got more fan mail for you than for Clark Gable or Elvis.

We got an awful lot of fan mail. One time in Central Park, it took two mounted policemen on their horses to save me from a crowd.

Have your grandkids seen U.N.C.L.E.?

I’m sure they haven’t. It’s not on TV, and there’s no real reason to start showing them Granddaddy when he was 30 years old.

People think the years between U.N.C.L.E. and NCIS were relatively lean for you, but weren’t you pretty busy?

I was constantly working and very happy, living in New York and married to Katherine. There have been some ups and downs. I lost my son Jason to an accidental overdose [in 1989]. That was a very low point.

You had adopted him with Jill. Did you know he had a problem with drugs?

He was going through a difficult period, and he got caught up in the whole drug culture in LA. I don’t think Charles and Jill were able to cope with it. When I went to visit his grave, they had it unmarked. They didn’t want to face the fact it had happened.

I had the grave marked properly, and we now celebrate on

Jason’s birthday. We take a six-pack and have one each and pour the rest for Jason.

What’s the secret to your long marriage?

Katherine and I are two halves of a whole. We work well together, and when problems come along, we solve them. The best thing about a marriage is you find out what the other person wants and make damned sure they get it.

How do you keep so youthful?

I do Pilates twice a week. I stick to a Mediterranean diet, which is basically no fat and no sugar. And I have good genes.

Is there anything left for you to do on your career bucket list?

King Lear sits out there, but I’m going to avoid it because it’s a terribly difficult play to do and an even harder one to watch.

Do you have any regrets?

I have no regrets. I’ve had a magnificent life all the way. — Reporting by Barbra Paskin