No time like now for television star Tony

He turned 70 in August and, although he isn’t “freaked out” by the number, says sagely: “It’s what I’m able to do or not do that’s the big issue, and I still feel able to do pretty much everything I did when I was 30, so it’s not a problem.”

The other driving factor behind penning his new autobiography, No Cunning Plan, was the issue of people’s preconceptions. After all, it’s hard not to think you know Robinson if you’ve grown up watching Blackadder and Time Team.

“I’m slightly less intellectual and slightly more larky than a lot of people might imagine,” the London-born star says wryly.

“My children are embarrassed by most of it,” he says of the book, but adds: “If that is going to be the criterion on which I’m writing the story of my life - whether I’m embarrassed or not - then really, I’m not going to get past chapter one.”

No Cunning Plan recalls everything from his first big acting role - in Oliver! at the West End when he was 12 - to the Blackadder years, and finishes up in 2006 - presumably leaving room for a second book.

It’s sprinkled with surprising little details that don’t really go anywhere, like the time he flirted - badly - with Liza Minnelli (“When you’re 13 or 14 and there’s an incredibly sophisticated girl you’re trying to chat up, you don’t remember anything about what you said, other than what a knob you were”), and how he fell under Helen Mirren’s spell when she told him that a tiny tattoo on her hand was something she’d “picked up in a brothel in Marseilles”.

“That’s so typically Helen Mirren, isn’t it? To tease you with a story like that and then just move on,” he says with a laugh. “Today, I’d say, ‘What exactly do you mean? Is that really true?’ But in those days, I just thought it was the sexiest thing anyone had ever said.”

Robinson, who’s also written a string of children’s books and recently starred as Greg Davies’ dad in comedy series Man Down, cannot say with certainty that writing No Cunning Plan was cathartic, but admits it was an emotional process.

“I hadn’t realised how moved I would be by going back to certain times in my life. Most of us just assume that when difficult things happen, we deal with it, we work it through and then we move on. But actually, most of the time, we don’t - if there’s an issue we just park it, and then move on, and ghosts of it are still ticking away.

“Coming back to those things that made you feel uneasy or upset, or humiliated or lonely, or all of those, there’s no doubt it does trigger some echo of those emotions in you.

‘‘My wife said my moods changed with which chapters I was writing.”

Robinson married Louise Hobbs in 2011 after they met in a restaurant - he needed a seat, and the only spare one was opposite her. However, she is only mentioned in the epilogue.

“She didn’t come into my life until after the time the book ended, but I didn’t want to exclude her from the book because she’s obviously the most important part of my life now,” he explains.

:: No Cunning Plan by Tony Robinson is published in hardback by Sidgwick & Jackson, priced £20.