I stumbled upon this book quite accidentally after watching a YouTube clip of Derek playing -- the clip itself was one of those "You might also like..." things that YouTube pops up when you watch something, so this was a very circuitous route indeed!
Aaaaaaaaaaaaaaaanywho, I found this book riveting from the get-go. Ockelford is a very good (and very funny!) writer, and clearly also a sensitive, intuitive and gifted teacher. He also has an uncanny ability as both biographer (of Derek) and autobiographer (of his own involvement with Derek) to step back out of the spotlight and let the story tell itself.
One quote late in the book sums up Ockelford's approach to his own writing, his work, and to Derek himself, particularly in regard to Derek's public appearances, the majority of which Ockelford facilitated (and for which, presumably, he has taken some criticism -- undeserved, IMHO): "... there were two main challenges: how to give people an idea of things in everyday life that Derek found difficult without demeaning him, and how to depict his exceptional talents without indulging in freakery."
This book does both, beautifully.
And I was delighted to learn recently that Mr Ockelford has another book forthcoming, which I cannot wait to read.