Peter, not at all - very glad to hear from you !
I've had a brief look on the web for colour pictures of the four aircraft, and WP861 seems to figure largely. Apparently it was the aircraft that the Duke of Edinburgh learned to fly in. I had no idea I'd sat in the same bucket seat as Phil the Greek. It has strange black strips either side of the fuselage roundel, and I'm not sure of the significance of those.
Do you have anything of the other three aircraft in your collection ? If not, I'll look for more of WP861 - she still flies in the USA, reg N861WP.