  This arXiv submission is posted primarily to make available some additional
material to what we prepared for the Derek Memorial article published in the
Notices of the AMS. We start (with the permission of the AMS) with the text of
our submission close to the final published version (which you can get online.
After that we include some autobiographical notes that Derek dictated to Louisa
Barnsley (whom we thank) during his final illness. Finally some unpublished
notes Derek wrote on the history of his seminal monographs with Bratelli. We
thank Marion Robinson for permission and encouragement to post these items.
