OK, now I am confused!-F means "Recovery mode for a non-importable pool."
-n means "don't actually do it, just see if it might work"
https://www.freebsd.org/cgi/man.cgi?zpool(8)
I've ran the command "zpool import -fFn -R /mnt vol1" and now when I run a "zpool status" the volume is listed, and I can access the data from the CLI.
It's been up for a about 15 minutes now and not yet crashed? I can't see the data in the GUI yet but I believe that is a case of waiting for it to show up is it?
Question is why has this worked OK as the Fn shouldn't have done anything should it? Essentially what I've done is run "zpool import -f -R /mnt vol1" is it not? Or am I missing something (most likely) about that command that has done something extra?
What's my next steps however?