Michael J. Fox has recalled his “nightmare” experience sitting next to Princess Diana at the premiere of ‘Back to the Future’

And whilst Michael loved meeting Diana, he said sitting next to her was “agony”, because he spent the entire length of the movie desperate for a wee.

Speaking during an appearance on ‘The Tonight Show starring Jimmy Fallon’, he explained: “She was sitting next to me. The lights go down and the movie starts, and I realise I am one fake yawn and an arm stretch away from being on a date with her, which is hilarious.

“The movie started and also, I had to go pee. So, for the rest of the movie, I’m sitting there, like, dying. I can’t say anything to her and I can’t walk away from her, because I can’t turn my back on her.

“So, it was just agony. It could have been the greatest night of my life, but it was just a nightmare. A pee-holding nightmare.”

When asked if Diana liked the movie, Michael added: “She seemed to laugh a couple times.”

Meanwhile, Michael recently said he was planning a “second retirement' from acting, after first stepping away in 2000 as he battled Parkinson's disease.

Writing in his new book, 'No Time Like the Future', Michael explained: "The nascent diminishment in my ability to download words and repeat them verbatim is just the latest ripple in the pond.

"There are reasons for my lapses in memorisation – be they age, cognitive issues with the disease, distraction from the constant sensations of Parkinson's, or lack of sensation because of the spine – but I read it as a message, an indicator.

“There is a time for everything, and my time of putting in a twelve-hour workday, and memorising seven pages of dialogue, is best behind me.

"At least for now."