Got this reply from the BGS...
Hello Dan.
Thank you for your online enquiry. I have scrutinised the signals from
the nearest BGS seismograph sites to you for a good few minutes either
side of the date and time stated (10 January 2008 @ 22:30 UTC) and can
inform you that there was no evidence of a seismic disturbance, of any
kind, detected by the BGS seismograph network.
Regards,
Julian
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Julian Bukits
British Geological Survey
So it shall for ever remain a mystery.....
Cheers
Dan