"I did camp myself up," admits Russell Grant. "I think trying to act yourself is the most difficult thing you can do on screen."
The nation's most popular horoscope isn't talking about his weekly outings for the Strictly Come Dancing competition, but his role in British comedy-thriller Kill Keith, where he joins stalwarts Keith Chegwin, Tony Blackburn and Joe Pasquale in a satire about breakfast television billed "Saw meets Richard and Judy".
"What you actually see on there is a parody of myself," explains Grant. "It's me as the public sees me, rather than me as I actually am."
Hard as it is to believe, the off-screen Russell Grant is another entity entirely, according to him:
"One's a performer and entertainer, and the other one is shy. I don't go to parties, premieres, first nights, any of that. I like to stay at home, and read two books at a time."
For Grant, this foray onto the big screen represents a return to the acting of his youth as well as a reunion with his old friend Cheggers:
"We appeared together in Tom Brown's Schooldays at the Cambridge Theatre back in the 1970s, and we've been friends since those days. Other names included Simon Le Bon - I don't think he needs any description. Keith and I always stayed in touch, and he rang up and asked if I would play myself."
It turns out Grant is also keeping a longtime family flame burning:
"This film is a really British black comedy, almost like Hammer House of Horror, which is where my uncle first started working. It ended with him winning an Oscar for The Deer Hunter, so it's great to be involved in something that carries on my family's movie tradition."
With such a history behind him, how did Grant end up being the nation's favourite happy horoscoper?
"I was working at the London Palladium, and astrology was just a hobby, before I was asked to do the ideal home exhibition," he remembers. "But it hijacked the career once there were pictures of me with the Queen Mother, they called me the 'astrologer royal' and it became a fait accompli. I could either stand my ground and continue acting, or do the sensible thing and take the BBC’s offer to become their breakfast time astrologer."
These days, though, star-gazing is firmly in the background.
"I learnt my lesson way back, and let astrology take over my career," Grant reflects now. "I'm 60 years old, I'm living the dream, I'm back to theatre, and astrology will remain in its place. I'm back doing what I really love to do."
Kill Keith is in cinemas from today. Strictly Come Dancing is on Saturday and Sunday evening on BBC1.