I should have tried this before posting..
So what I basically did was, create a new cluster (enabled VSAN).
Went to the cluster where the hosts were participating and showing the error "host is in a virtual san cluster but does not have virtual san service enabled".
Then disconnected each host, then removed each host.
Then I added each host one by one to the new cluster I created with VSAN enabled..
I now just have an error on each host where I see my system logs are not on persistent storage.. I recollect the VSAN datastore is not a place to put my system logs, so I'll look at putting a syslog server in place.. any suggestions for a good syslog server (free) ?
Thanks
Paul.