M14 - its very unlikely that the individual was from the CAA.
They will always make an appointment to see you and not discuss details over the telephone. I know having being involved on both sides more than once.
As for tracing your details, well - it's not 'big - brother', it's simple access to the CAA aircraft register which anyone can access at any time, when the aircraft was registerd to your flying club/group you gave this permisssion, knowingly or otherwise.
It doesn't take up to much time to trace a telephone number of the operator thereafter.
Unfortunately, some of the advice given in replies to your post are very misleading, the CAA are successful in the majority of prosecutions, but I don't think you have anything to worry about.