Actress Sian Phillips, still going strong at 82, looks back on her remarkable career before a return visit to Glasgow

And of course Phillips has played some of the most formidable women ever written about, from Ibsen’s Hedda Gabler to her role as Livia in 1976 in I, Claudius. Her Joan of Arc in St Joan suggested the actress could still smile benevolently while burning.

But it’s all a Bafta/Olivier winning act. This is a lady, you discover after ten minutes of conversation in a quiet corner of Swindon’s Wyvern Theatre, where she’s appearing in The Importance of Being Ernest, who is far from invulnerable at all.

“I’ve never felt I knew how to do this,” says the smiling eighty-two year-old of acting, as if to suggest such an assumption to be absurd.

“I get nervous, I still get nervous, until I feel I’ve got my character.”

Phillips knew she wanted to become a performer as a four year-old child growing up in Wales, appearing in a church performance (“I wanted a world of gold and glitter”). After graduating from the University of Wales, she landed a scholarship to RADA (her contemporaries were Diana Rigg and Glenda Jackson) where she shone like a beacon at drama school, to the extent she was privately funded, via the drama school, by a secret millionaire. But acting was never about money or fame. In fact, she explains the theatre world at the time frowned on the world beyond the stage,

“When I was still at RADA I turned down five film contracts and several West End plays,” Phillips recalls. “My teachers expected me to and that was the culture. And my training was for the theatre, and so I agreed. Even when the cosmetic companies approached and asked me to become the face of Revlon or whatever and offered the equivalent of a £1m today I turned it down. I was told to take the work would be theatrical suicide.”

Phillips sighs and smiles; “I went to RADA at the time when actors were told not to take curtain calls. But of course a minute later it had all changed.”

The Fifties was a time before women gained the right to be listened to. However, the actress maintains she never encountered sexism in the business. “I realised later however I was being paid less than men in lesser parts, but I didn’t know at the time. But I did experience sexism in my private life.”

Ah, yes, the O’Toole era. Phillips had two daughters with the iridescent but demanding star, and a hell of a time of it. “When I was about to marry O’Toole, all my friends and the big guns in theatre were wheeled out to say ‘Don’t marry this man or you’ll be ruined’ but I just adored him, and he was such a talent, which is so seductive.”

She worked with her husband in theatre and on film, but he wasn’t at all happy about it. “You couldn’t make a stand, it just wasn’t done. Plus, I think I wasn’t the type of person who was strong enough to do anything about it. I didn’t have it in me.”

O’Toole wouldn’t even read lines with her. “Oh God, no! I was one of those actresses who learned her lines with a script propped up against the sink wall as I washed the dishes, or upstairs on a bus. Meanwhile, O’Toole had his study and insisted on quiet going on around him.”

Phillips’ lack of ego has, most likely, caused her to suffer at the hands of more demanding men, but it also makes her more delightful. For example, when I, Claudius (and her performance) was being hailed as genius, she was entirely unaware.

“I didn’t even know it was so popular in America. Nobody told me. And the media was so different in those days. But you know, I’ve loved everything about the business except the fame.”

Phillip says she’s loved the opportunity to continually learn, from the likes of Rex Harrison. “He was a mean man, but I’m quite good with bullies professionally, less so in my private life, and I got round him by rehearsing so hard on my own. But he was so good an actor that when we were on doing a scene and he stopped delivering lines and began speaking I couldn’t tell. It was scarily good, like being on ice with him.

“He also taught me to inhabit a stage, to feel the props, believe he furniture was my own. That way, the audience believes it.”

Phillips also learned from O’Toole. “While he was brilliant, people thought he was a natural. But I’ve never known anyone who prepared as much as he did. He knew everybody’s part in a play before it began, not just his own. He’d research every detail to within an inch of its life, all to make it look effortless.”

Phillips works hard to do the same, whether it’s playing Juliet at the age of seventy five ( the play set in a retirement home) or alongside close chum Elaine C.Smith in Calendar girls. She still worries frantically about getting it right, which was the case with her Lady Bracknell.

This production is not standard Oscar Wilde, it’s a play within a play, in which an am-dram outfit take on Wilde; the joke is the players are all too old for their parts. (Nigel Havers’ Algernon is around twenty nine, and Havers won’t see sixty two again.)

“I was offered the (original) play twenty years ago,” Phillips offers, “but I turned it down because I felt I was too old. Lady Bracknell has a daughter of nineteen. But then I was offered it in America, where Lady Bracknell is often played by men, so I thought if they can stage it with men who are the wrong sex – and too old – why shouldn’t I do it?

“So I did, and I was terrified every single night. In fact, I’m still nervous. The language, the sentence construction is much more difficult than Shakespeare. I had to put my nose to the grindstone to make it work. But I feel I’ve got her now.”

Phillips still feels the nerves, (yet still commands stage wonderfully.) But she won’t stop performing.

“Oh my God know. I’ve had a lot of second chances late in life. Most people taper off at seventy, but over the last ten years the plays have come in and it’s been a great gift. And when I’m out there, and I feel I know the part, I love every moment of it.”

• The Importance of Being Ernest, The King’s Theatre, Edinburgh, November 10-14, The Theatre Royal Glasgow, November 24-28.