The art of collecting as many ID designations of aircraft as possible in a single lifetime, almost identical to trainspotting except for the aviation/train aspect. Apparantly is uniquely British unlike the global dominance trainpotting has achieved. The best place to see planespotters is at Heathrow airport, you can spot the spotters by looking out for their thermos flasks, biros and notepads and their aura of complete harmlessness. The worst place to spot planespotters is at Greek military bases (see below)

This has risen to national prominence in the UK at this moment due to the fact that 10 British (and two Dutch) planespotters were arrested in Greece for spying and are not being let go, before this most British people did not know such hobbiests existed either. These ridiculous arrests were caused because the Greeks, being the inventors of philosophy and all, could not (and still can't) believe in the existence of such a banal "pleasure" pastime of spotting planes. Due to this cultural incomprehension, the Greek's are more willing to believe that these are MI6 James Bonds disguised as utter nerds working in partnership with their sworn enemy of Turkey to undermine the Greek Air Force by, uh, copying down the very very large letters and numbers painted in white paint on the side of their helicopters. ("I say what an ingenious plan M! Very KISS what what!!").