Hi again
As mentioned, the following GUCS were changed as follows and the pg_basebackup seems to have worked. We are moving this instance to a new cloud platform in due course and we will be using version 9.6.5
wal_keep_segments = 48
wal_receiver_timeout = 5min
wal_sender_timeout = 5min
Problem solved
Many thanks to you all
Douglas Reed
DBA
FSB Technology
