Jean Marsh, the actor and writer best known for co-creating and starring in the 1970s TV show Upstairs, Downstairs, has died aged 90.

The film-maker Michael Lindsay-Hogg, who was a close friend of Marsh, said she died of complications with dementia in her London home on Sunday.

“Jean died peacefully in bed looked after by one of her very loving carers,” he said. “You could say we were very close for 60 years. She was as wise and funny as anyone I ever met, as well as being very pretty and kind, and talented as both an actress and writer.

“An instinctively empathetic person who was loved by everyone who met her. We spoke on the phone almost every day for the past 40 years.”

Upstairs, Downstairs, covering class relations in Edwardian England, ran for five series from 1971 to 1975 in the UK and was also screened in the US. It won seven Emmy awards and a Peabody award, and Marsh won the Emmy for outstanding lead actress in a drama series in 1975 for her portrayal of Rose, the head parlour maid of the elegant Bellamy family that the show centred on.

Marsh also co-created The House of Eliott and appeared in films such as Cleopatra in 1963, Frenzy in 1972, The Eagle Has Landed in 1976, The Changeling in 1980, Return to Oz in 1985, Willow in 1988, Fatherland in 1994 and Monarch in 2000.

She became known for her appearances in the Doctor Who universe, including Joan of England in The Crusade, then as Sara Kingdom, a companion of the First Doctor. She later portrayed a villain opposite the Seventh Doctor.

Marsh was awarded an OBE in 2012 for services to drama.

The actor was born as Lyndsay Torren Marsh on 1 July 1934. She was six when the blitz began, and at seven she started ballet classes and took an interest in the performing arts. Rather than pursuing a traditional career, Marsh went to theatre school – which her parents considered a practical move, according to the New York Times.

In 1972, she told the Guardian: “If you were very working class in those days, you weren’t going to think of a career in science. You either did a tap dance or you worked in Woolworths.”

Marsh came up with the idea for Upstairs, Downstairs with her friend the actor Eileen Atkins when the pair were house-sitting at a wealthy friend’s house in the south of France. After explaining that she wished she lived in luxury more often, Marsh got the idea to create a show that explored class relationships within household dynamics.