Her father, Harry Llewellyn Jones Lewis, was a haulage contractor but when her mother, Florence Edith (born Brewington), married again she took the surname of her step father John Thomas Thorndycraft in 1937.
She began teaching history at Peckham Girls' School in 1958 where the head, Margaret Clarke, was active in the National Union of Teachers (NUT).
[2] She was still active in the NUT during the 1980s where she supported a less militant approach to industrial relations then some within the union.
[2] She had played a key role in the development of the "CSE" qualification and in persuading the government to fund a single exam "the GCSE" for secondary children at age 16.
[1] During her first speech to the union she criticised those who were whinging and argued that the NUT needed to "achieve change from within".