Many of her school performances, therefore, are what she calls "progress concerts": "They are not necessarily polished, they consist of what the children have been working at in class. I don't want to be seen as the musicspecialist who has put on thiswonderful concert which is all my own work."
Her music lessons are impressive for the way they involve children of every ability. Last week she began by gathering all the children into a seated circle on the floor, where she led them in the singing of a Jewish "Shalom" using only two tuned percussion bars as accompaniment.
After some rhythm exercises, and discussion of the difference between major and minor chords, Ms Sefton set groups to extend the "Shalom" by composing some extra material using classroom instruments. All the pupils were interested and trying hard, despite the wide ability range.
These pupils are accustomed to composing. Last year the school had time with a composer-in-residence, arranged by Berkshire local authority. Ms Sefton says: "I wanted some help in extending beyond my own ideas, and I wanted the other teachers to see a composer working with the children and valuing their ideas."
Meadow Vale is well equipped with classroom instruments, but Ms Sefton makes much use of the least expensive instruments of all - the voice, and the two hands clapping. She teaches songs simply by singing them: "I use the piano very little."
Much of her work is to do with giving confidence to non-specialists on the staff. She also runs practical workshops for colleagues in other schools as well as using her co-ordinator role in a supportive way.
Sandra Thornton, Meadow Vale's head, said: "Mary will plan a lesson together with a teacher, and then help to teach it in the classroom, observing the teacher and having a discussion afterwards. It's a model that works."
Meadow Vale primary, 01344 421046