G-CELP landed at LBA (no emergency squawk was given) and the flight is now underway again as EXS857A with C-GDFM doing the honours. Incidentally, I live and work about 10 miles from LBA. Will have a nosey and see if I can find anything.
There was no emergency squawk and plenty of time to fly in circles burning fuel off and reading the handbook, so my money would be on a non-urgent tech fault.