Tony,

Following the death of Keith in 1991, great loss that it was, Val Marsden John O'Hagen and Graham Pirt the remaining members of Cockersdale put togethera book of his songs.

Its called Picking Sooty Blackberries" published by Fellside Music in 1992 ISBN 1 871318 01 7

I'm not sure if its still in print or if there are copies available but it worth a try.

Hope this is of use

Andy Barnes