Pg_rewind cannot load history wal

We have been struggling to get pr_rewind to work. In desperation we have been trying to make the use case as simple as possible:)

We have two databases servers running Postgres 10 on two different machine in the normal Primary/Standby configuration.
Both machines write their WAL archive logs to the same shared drive (called /ice_dev/wal_archive).
The configuration has the following terms
archive_mode = always
archive_command = 'test ! -f /ice-dev/wal_archive/%f && cp %p /ice-dev/wal_archive/%f'
full_page_writes = on
wal_log_hints = on
Checksums are enabled

Our procedure that runs on machine A and B is as follows:

1. Build new databases on A and B, and configure A as Primary and B as Standby databases.
2. Make some changes to the A (the primary) and check that they are replicated to the B (the standby)
3. Promote B to be the new primary
4. Switch of the A (the original primary)
5. Add the replication slot to B (the new primary) for A (soon to be standby)
6. Add a recovery.conf to A (soon to be standby). File contains recovery_target_timeline = 'latest' and restore_command = 'cp /ice-dev/wal_archive/%f "%p"
7. Run pg_rewind on A - this appears to work as it returns the message 'source and target cluster are on the same timeline no rewind required';
8. Start up server A (now a slave)

At this point A is in a read only mode but not replicating. Its logs contain the following repeating message

2018-08-01 20:30:58 UTC [7257]: [1] user=,db=,app=,client= FATAL: could not start WAL streaming: ERROR: requested starting point 0/6000000 on timeline 1 is not in this server's history
DETAIL: This server's history forked from timeline 1 at 0/57639D0.
cp: cannot stat '/ice-dev/wal_archive/00000002.history': No such file or directory
cp: cannot stat '/ice-dev/wal_archive/00000003.history': No such file or directory
cp: cannot stat '/ice-dev/wal_archive/00000002.history': No such file or directory
2018-08-01 20:30:58 UTC [6840]: [48] user=,db=,app=,client= LOG: new timeline 2 forked off current database system timeline 1 before current recovery point 0/6000098
cp: cannot stat '/ice-dev/wal_archive/000000010000000000000006': No such file or directory

We can see the 00000002.history file in B's wal directory.....but it never appears in the wal_archive directory - not even if we issue a checkout or even restart the server.
00000003.history does not appear to exist on either of the machines.

Any ideas what we are doing wrong?
Thanks. Richard

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