Miriam Margolyes has revealed that her parents once made her swear on a Bible not to sleep with women.

The 74-year-old actress is known for her role as Professor Sprout in the Harry Potter films, as well as for voice-acting and films including The Age of Innocence.

In a new interview with Audioboom, the actress – who has been with partner Heather Sutherland for nearly five decades – spoke candidly about her experiences growing up, and coming out to her parents in the 1960s.

She said: “People who were gay were pitied and ridiculed by my parents – they had no modern sense of people being allowed to be who they were.

“And I didn’t tell my parents, in fact, until I was something like 27. My mother was utterly appalled and disgusted… and she told my father, although I didn’t want her to.

“She told him, because they shared everything, and they made me swear on the Bible in the drawing room, in the most formal way, that I would never sleep with a woman again.

“Extraordinary really, as my father was a doctor and in many ways he was an enlightened man especially around racism. But about homosexuality… never!”

She added: “The curious thing is that I embraced homosexuality with as much joy and delight as I’ve embraced everything else in my life.

“It isn’t a problem for me – and I’m perfectly happy. I want everyone else to be perfectly happy about it.”

Of her partner, she said: “I have had a partner for nearly 50 years. We have been happy and loving and joyous and each other, and we still are.

“My only fear is she will die before me, or that I will die before her – and one of them is going to happen, unless we have a suicide pact. But I don’t think she’s up for that!” Fellow Harry Potter star, Evanna Lynch, who played Luna Lovegood, has sent out a strong message to homophobes who follow her on social media.