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 Danced with the Scottish Ballet, Royal Academy of Dance, Royal Ballet School, and Susie is on DUK's Honours Advisory Committee.
3. Susan Cooper, 1947- wrote "Preparing, Designing, Leading Workshops"
4. Susan Cooper (Susan Elizabeth The textile touch