There is more than one Susan Cooper here:
1. Susan Mary Cooper (b. 1935) has written fantasy books and (according to her website) the J. B. Priestley book as well.
2. Susan Cooper, PhD, author of Staging Dance, is a ballet dancer and choreographer who is head of the BA program at Urdang Academy in the UK
3. Susan Cooper, 1947- wrote "Preparing, Designing, Leading Workshops"
4. Susan Cooper (Susan Elizabeth The textile touch