Herald production
Two good reference books on the subject,
Handley Page Herald by Graham Cowell published by Janes 1980 ISBN 0 7106 0045 3
Handley Page aircraft since 1907 by CH Barnes published by Putnam 1976 ISBN 0 85177 803 8
Full details of production, customers, delivery dates and the eventual fates of each airframe.
Hope this helps,
om15