PEN 15 was (is still?) owned by Steve Parrish the motorcycle racer. He overtook me just outside Dover in 1992 in a Porsche 911 fitted with that plate.
I followed it around a multi-storey at Heathrow many years ago. One of those "did I really just see that" moments!
At an Air Cadet Flying Establishment I used to frequent the OC had the plate G18 VGS.