Brian Cox was "touched up" by Princess Margaret when he met her as a younger actor.
The 73-year-old actor has claimed that the late royal - the only sibling of Queen Elizabeth II - run her fingers down the inside of his shirt when the pair met in 1969 at The Royal Court Theatre in London, leaving him dumbfounded as to how to react.
In an interview with The Guardian newspaper, Brian said: "You know, when I was a young actor I was touched up by Princess Margaret. I was at the Royal Court. I was doing a play with Alan Bates and it was my 23rd birthday and I'd been given a red shirt from Lindsay Anderson. I'd just washed my hair so I was sort of glistening, and I walked in and was introduced to her. She put her fingers on my shirt, and said, 'This is a lovely shirt.' And she started to run her fingers down the inside of my shirt. And I went, 'Uh oh!' What do you do when you're being touched up by a royal?"
Brian can recall his fellow actor James Bolam noticing Margaret's overtly flirtatious behaviour but despite her advances nothing developed between him and the princess - whose parents were King George VI and Queen Elizabeth.
The 'Succession' star explained: "It was so funny. James Bolam, he could see what was going on and started going 'Ooooh' out of the side of his mouth, which somehow said princess didn't take in at all.
"She just kept saying, 'You were so wonderfully hooded on stage. I wanted to know more about you.' She was an extraordinary creature. I excused myself and said, 'Thank you, ma'am,' and it came to a natural end."
Brian also confessed to the publication that he has smoked cannabis and he recommends that everybody takes the herbal drug because it helps you deal with "idiocy".
He said: "It's absolutely great and I recommended it to everyone - get stoned! It does make the politics easier to bear. It's a way of dealing with idiocy."
The 'Churchill' star only began smoking the drug at the age of 50.
He added: "I didn't start until I was 50. I was very against it, actually. You know, I got married at 21 to an upper-middle-class English girl - well, with Scots parentage, but you know English Scots are the most English.
"We had two children, one went to St Paul's, one went to Cheltenham Ladies College. It was all done proper. It wasn't who I was, but happy wife, happy life.
"Then when I was 50, I realised I missed out on what was going on with young people because I was so square, and I was working so hard, I needed something to relax. So I discovered the wonderful world of cannabis."