Kate O'Mara was given her first big break by Peter O'Toole, and starred opposite Jeanne Moreau, Jack Hawkins and O'Toole himself in Great Catherine by George Bernard Shaw.

You might think this an intimidating prospect for a young actress, born in Leicester, but not for this formidable woman (accent on the first syllable, incidentally).

O'Mara was born into the fifth theatrical generation of her family, something which she says helped her to cope with, but not avoid altogether, the hazards of a sometimes pernicious business.

"There's no avoiding pitfalls in life", as she says. But she made her stage debut at the age of four, and learned from a young age what the acting business had in store.

"It made me realistic and philosophical about it. My mother warned me about what can happen (going without work for some time). It happened to her and it certainly happened to my sister."

She joined what she calls the family business, an "inevitable" move. Her great-grandparents built and performed in their own theatres in the days before cinema and television, where O'Mara herself has prospered in roles as romantic lead, vampire, vamp, and latterly mature and powerful woman.

O'Mara, 66, plays Lady Edna Chesterford in Ealing Comedy The Titfield Thunderbolt, which is coming to the Theatre Royal, Windsor.

Of her character she reveals: "She's an aristocrat, and the aristocratic women got the country through two world wars. The upper classes were very much in control at that stage, and I play a woman who is in control, and used to being in control.

"I enjoy playing power freaks, probably because I am a bit like that in real life. But Edna's a good egg, if a little patronising at times."

The play tackles the issues of conserving traditional ways of life, and the needless destruction of the rail services wrought by bureaucracy.

"The Ealing comedies were subversive and very ahead of their time. This play is current. There is always some corner of England that we are trying to protect. Today the rail service is non-existent. We used to have decent railways. If I'm working in London I use the train or the bus, and I am perfectly happy to do so, but outside of London I have to drive a car whether I like it or not, there are no trains or buses. That's short-sightedness on the part of the government, and the wonderful thing about this play is it takes the government to task in no uncertain terms. I have one particular speech about bureaucracy, which was written in 1952, but which brings down the house. It is easily recognisable by a modern audience."

O'Mara has worked with some giants of screen and stage. Trevor Nunn and Peter Hall come to mind, but clashes don't scare her.

She says: "I enjoy conflict. If someone shouts at me, I shout back. I am not intimidated by these people. I like to take them on."

I suggest that she may have been the one to initimidate others.

"Well, only if someone does something foolish."

O'Mara returns to comedy in The Titfield Thunderbolt after several previous outings, notably with Eric Sykes in The Plank, who said lately, "If I'd known how good Kate was, I'd have given her Tommy Cooper's part."

She also appeared with Morecambe and Wise. She holds good comedians in great esteem: "I saw Eric and Ernie in what I thought was an animated conversation, but then realised they were rehearsing. The great thing they comedians do is make it look easy, but it is the most difficult thing in the world, to make people laugh. I only hope we get a few laughs at Windsor. I am so looking forward to going back. It's a wonderful theatre."

Titfield Thunderbolt is at the Theatre Royal, Windsor, September 20 to October 1.

Tickets: 01753 853 888