Thank you to all who offered advice and help in the recent crash, including those who commented, IM'd and emailed. The problem could not be fixed by remote, so I've reset the whole server and started again from scratch (using last backed up OARs and IARs)
This last week Bernicia has been limping along on a standalone server with SQL Lite (the problem was so bad that I couldn't even get a working MySQL working). Now it is back to normal, running on Dreamgrid again with Robust and MySQL.
Thanks again to all those who contacted me, you have given me great confidence in the Opensim Community.