Kier's redirection script worked fine - everything appeared to be redirected.
Upgraded to 1.3.5 and installed a couple of addons.
But now the old vb3 thread URLs are no longer redirecting.
Re-installed the redirect files on the old server, double-checked .htaccess rules and domain 301 direct - all seems to be there.
Is there any obvious reason why this might be the case? Have been slightly tearing my hair out trying to fix this.
EDIT:It may be that the table with the IDs has emptied, but I'm not sure which that might be? I have a table called archived_import_log, but if the IDs were stored elsewhere, I might be able to recover them from my test import.