Then way back in 1987 I remember very well publishing a young person's biography written by Betty Gilderdale and illustrated by Alan Gilderdale. It was called "Introducing Margaret Mahy" and we published it first in hardcover under the Viking Kestrel imprint; later it became a Puffin paperback. Sadly I cannot find a cover image but I have the book here in front of me and it features Margaret in her famous mulit-coloured wig. The photo was taken by Bruce Foster and looks to be on the Governors Bay Wharf.If anyone out there has a cover image I'd be delighted to have a copy via jpg so I could add it here.
It is long out of print but perhaps Penguin may now consider an updated edition?