My mother, Karthy Nair, who has died aged 90, was one of the founder members in 1954 of the People’s Action party of Singapore, which after independence from British rule became and remains the governing party.

Karthy was fiercely critical of the party leader and future prime minister, Lee Kuan Yew, whom she regarded as a British placeman, and she left Singapore in 1956 to settle in the UK. Karthy’s brother, Devan Nair, became a union leader and eventually president of Singapore, later falling from favour and suffering exile in Canada.

In 1960s London, Karthy mixed with writers, artists and musicians. A lifelong member of Liberty, the Campaign for Nuclear Disarmament and the Peace Pledge Union, she had a horror of nuclear war, and joined the protesters at Greenham Common. When I was a young man, our home in London was a safe rest house for women who needed a break from the camp.

She was born in Malacca, Malaysia, one of nine children of Sridevi and Karunakaran Nair, both from royal families of Kerala, south India. Her father willingly gave up his title and lands when India became independent, being persuaded of the justness of socialism. Karthy’s school studies were interrupted by the second world war.

Her family took refuge from the Japanese invasion of Singapore on the rubber estate that her father managed in Malaya. She had wanted to study to be a doctor, but instead went to teacher training college. In the UK she had to requalify, and noted with surprise that the training she received in London was inferior to that which she had completed in Singapore. Later, she was awarded a BA by the Open University.

She was a popular and inspiring teacher, first in secondary schools, where she gained the trust and respect of girls involved in street gangs around Ladbroke Grove, and then at Highbury Quadrant and Canonbury junior schools in north London.

A lover of poetry and theatre, and a fiercely independent thinker, after leaving Singapore she refused to join any political party because she would not be told what to think – relenting in the last two years and joining the Labour party in order to support Jeremy Corbyn, her local MP.

Despite her strong political beliefs, and a predilection for robust argument, friendship and loyalty were more important to her and she often exclaimed: “I can’t help it if some of my best friends are Tories!”

She is survived by two sons, Sagar, who was adopted, and me, from a relationship that did not endure.