She was shortish, dark-haired and very, very funny. When I was 11, I had a crush on her, and from then on she guided me gently up through the school, with her sense of the absurd carrying me through various dilemmas. I had several outstanding teachers, and I don't remember a single bad one. But where some of the others ruled by fear, Miss Thomas ruled by laughter.
She was a great stylist and couldn't bear fussy writing. Near Manchester High, there was an old-fashioned primary school teacher who used to teach her pupils flowery figures of speech. I learned from Miss Thomas that there would always be a certain proportion of 11-plus papers from that school with compositions that included the phrase "vast panoramas of undulating countryside" - the kind of thing she couldn't stand. She also used to say over and over again that punctuation was an integral part of a sentence, not a little decoration to be added on as an afterthought.
About two lessons before our end-of-year exams, or O-levels, she came in to teach examination technique - a lesson that always began with "Read the questions carefully". She would then encourage us as follows: "Always appear to answer the question, but if you don't know how to answer it directly, then stick to your own angle." She knew that there was a psychology to examiners and that you had to play along with them.
She had a brisk, no-nonsense teaching style. There was hardly any bad behaviour, but if someone did step out of line, Miss Thomas fixed that girl with her eye and ridiculed her. She never exploded but she could be crushingly sarcastic.
I was sometimes quite a sad child. Miss Thomas had no direct pastoral role - she was never the sort of person to whom you would have gone and discussed a personal tragedy - but she always knew how to prick that inner bubble of merriment within me, especially when she was producing the school plays.
I am an actress as well as a historian, and more than anyone else Miss Thomas encouraged my love of theatre. The standard of drama was very high. We did Androcles and the Lion and, when I was 16, a wonderful version of Twelfth Night in which I played Maria, and she brought gales of laughter out of me.
She was a splendid director - so good that if she had not been a teacher she would have been a professional director.
She eventually became head of English, but has been retired for 20 years now. Not long ago, she invited me to her 80th birthday party. That was the first time I ever called her Jean, and it was then that I found out that she has never been a great Christian believer. As a teacher, however, she believed in the value of the Bible. She was a fine reader and when the Authorized Version stopped being read aloud in church and was replaced by the New English Bible, she lamented that a whole generation of children would grow up without a sense of cadence. Speaking as an actress, I think she was right.
I went to Somerville College, Oxford, to read history but decided to switch to English, and the feeling for Shakespeare and Elizabethan poetry that I picked up from Miss Thomas made the change very easy. She was particularly good on the Metaphysical poets, and when I was doing my Oxford finals I found quotations flooding into my head that she had thundered out in the classroom at Manchester High.
She taught with love and jokes, and 20 years after I left Manchester High, when I worked as a special needs teacher in London, I tried to do the same. I realised then how much I owed her, so too when I co-founded The Poetry People, a recital and recording group which I'm still involved in.
I'm sure she was responsible for my sense of professionalism. I'm scatty and chaotic, but anyone who has worked with me would say "Maria's a pro". The self-discipline you need to be precise in your research and writing and to meet deadlines began with Miss Thomas. All of her caveats on style and her lectures on the importance of the semi-colon have paid off.
Maria Perry, historian and actress, is the author of "Sisters to the King", about the sisters of Henry VIII, and "Knightsbridge Women". Her new book, "Mayfair Madams", a history of the London district's duchesses, dancers and call-girls, is published by Andre Deutsch on May 19. She was talking to Daniel Rosenthal