Billy Connolly has revealed how he kept his cancer diagnosis a secret on the set of new comedy What We Did On Our Holiday, even though he was playing a character with the disease.

The Glaswegian funnyman, 71, said he withheld the information from his directors and co-stars to avoid special treatment during filming.

"I told them after it was finished. I didn't want to be treated any differently from anyone else," said Billy, who announced last year that he had undergone successful surgery on his prostate, and was also being treated for Parkinson's disease.

"It would really break my heart, to be a special case. So I just got on with it."

In one scene, his character Gordy, a grandfather preparing to celebrate his 75th birthday, must discuss his illness with his daughter-in-law Margaret (played by Amelia Bullmore).

"I had to say, 'I've got cancer'. Amelia didn't know I was telling the truth," the comedian said with a laugh. "I'd never said that to anybody in my life before, and there I was saying it."

The father-of-five, who is married to former Not The Nine O'Clock News star Pamela Stephenson, said he hasn't changed "a single thing" about his lifestyle since his diagnoses, but admits to being "kind of clumsy sometimes" as a result of the Parkinson's, and is struggling to play the banjo as well as he used to - "which is a pain in the butt".

It didn't take the comedian - who also wears hearing aids - long to see the lighter side of his health problems, "because I've always been on the outside of it".

"At one point, I went to see the doctor when they discovered I had the cancer thing. He was doing a drawing of my kidneys and prostate and how it works and the bladder and stuff, and he said, 'You're not going to die'," Billy recalled.

"I was absolutely shocked - it never crossed my mind that I might die. I said to myself, 'Of course I'm not going to die!' So I've never been deeply involved with it in that sense.

"I don't go on the internet and look up Parkinson's disease and see how I'm getting on. F*** that. I just live my life and it's clumsy and that's it."

:: What We Did On Our Holiday is in cinemas now.