My grandmother, Diane Brace, who has died aged 87, spent her life in education and political activism. She was principal of North London College - now City and Islington College - as well as national chair of the Association for Liberal Education and UK president of the Women’s International League for Peace and Freedom.

　　Diane was born and brought up in Kingston upon Thames, Surrey, the daughter of Dick Collingwood-Prince, a civil servant and osteopath, and his wife, Kitty (nee Harvey), a seamstress, both strict communist vegetarians. As a child she would distribute anti-Franco leaflets with her parents; she grew into a Labour supporter and campaigner, save for the period 2003-2007, when she cancelled her membership due to the Iraq war.

　　Diane attended Tiffin school and then went to the London School of Economics in 1948, where she studied politics and economics under the philosopher Karl Popper. Her classmates included future cabinet ministers and global financiers, and also Derrick Brace, whom she married in 1951; they had two children, George and Catherine.

　　She began her career as a primary school teacher at Molesey junior school, with a class of 40 seven-year-old boys, after which she claimed “everything was easy”.

　　The most lasting relationship of her life was a friendship that began in 1945, when Diane drew a name out of a hat at school to select an American pen-friend. Over some 73 years Diane and Phyllis Stuckey (later Yingling), from Baltimore, came to write hundreds of candid letters to each other, helping each other to weather misfortunes, including the end of Diane’s marriage in 1966, and the death of her son, George, in 1979, at the age of 27.

　　In 1980 Diane took a sabbatical from her job as a lecturer in liberal studies at Brooklands College in Weybridge to study politics and sociology at Birkbeck College under Sir Bernard Crick. She then became the first female staff tutor at the Further Education Staff College, and was in 1986 appointed principal of North London College. In her four years there she made equal opportunities a priority, starting a mentorship programme for ethnic minority students.

　　In the early 1990s, she set up and ran Greenwich University’s masters’ programme in public sector management.

　　After retirement at the age of 71, Diane threw herself into activism again, joining the WILPF. She also hosted a popular and vibrant seminar in Islington on current affairs for the University of the Third Age, applying the teachings of Popper.

　　She is survived by Catherine and four grandchildren, Victoria, Emma, Charlotte and me.