I think about my schooldays very fondly. I went to a very, very small private school, Streatham House in Crosby, Liverpool, and they were more interested in whether you held a knife and fork correctly than in education. I recall one time in the hall when everybody was applauding because somebody got two GCEs.

It was not what you would call academic. It was more like St Trinian’s. We were quite wild. We blew up the kitchen in cookery class. Someone left a glass bowl in the oven and forgot to take it out. We never had another cookery class.

But my life there did change because of one particular teacher. I had a semi-interest in history and a semi-interest in literature, but nothing else. There was no theatrical input from my family whatsoever. The nearest thing we had to going to the theatre was the circus.

Then Miss Dawn McCormick arrived to do speech and drama. Dawn McCormick was very tall and had an amazing figure. She used to wear high, spiked-heeled shoes and make-up, glossy lipstick. I had never met anybody with glossy lipstick before. She had slightly bucked teeth and she always had a little film of lipstick on her teeth which she would remove with a finger. She used to wear gorgeous perfume and I would move my chair closer to have a sniff. I thought she was wonderful.

Apparently she had been an actress and she must have been frightfully bored by having to teach these children. She would fling out poems for us to read. It was the first time in my life I wanted to please somebody. I just wanted her to say it was very good, but she never said that to anybody.

One day she asked us to read some Elizabethan poetry. Afterwards she called me forward and said: “You do know when you read a poem you are not supposed to move. Try to keep still.”

I got a glimmer of hope that she began to like me. One day she said: “Have you ever thought of doing some acting pieces, Lynda?” That was it. She caught me completely and utterly and changed my life. Everything clicked and I started to go in for all these acting exams.

She said to me: “There is a college in London called Rada. Have you ever thought of being a drama student?” If she had said: “Have you ever thought of taking up surfing?” I would have said yes.

She started training me to do audition pieces for Rada. I remember saying to my father I was going to go to Rada. He said: “Is it a kid’s outing?”

I remember my audition. I was 15 years old and I arrived at Euston with a map looking for the Royal Academy of Dramatic Arts. I was so naive. I said I was going to do Jean Anouilh’s The Lark, about Joan of Arc, a young French girl. I was interrupted by this voice saying: “We do know who Joan of Arc is. Just get on with it.”

I had these high-heeled shoes on and I thought I couldn’t do Joan of Arc in high heels, so I asked if I could take them off. The voice said: “I don’t mind if you take them off.” I had a really tight underskirt, so I asked if I could that off.

The voice said: “I don’t mind if you take it off, as long as you don’t take anything else off.” But I got in and got a scholarship and it was all down to Dawn McCormick.

Lynda La Plante’s ‘Above Suspicion: The Red Dahlia,’ airs on ITV1 this week. The actress-turned-screenwriter is known for a string of TV hits, including ‘Prime Suspect’ and ‘Trial and Retribution’. She was talking to Nick Morrison.