Pup,
Does this:
albeit written down incorrectly, so no calls to the CAA
and
When I looked it up on the CAA site it was clearly not the aircraft she saw
mean that if there would have been a PA28/C172 with the registration that your wife had written down (and we now know to be incorrect) you would have rung the CAA and thus caused distress and hassle to an unsuspecting pilot?