Pythagoras, I hope you photocopied your logbook before sending it to the CAA. If not, I guarantee you will the next time you need to send it to them!
Your logbook is probably one of the few irreplaceable possesions you have. The CAA have details of your license, and can re-issue it. The DVLA can re-issue your driving license. Your passport, birth certificate, etc. can all be replaced. But there is no way of replacing a logbook. I believe there are ways around it if you do lose it - signing an affidavit to say how much time you've got - but I'd rather not find out.
FFF
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