I've seen quite a few recently. Try Sloane st or Bond St. Not seen a purple one though. Good luck
Saw a few in exotic and leather on display for sale at H Sloane Street and Harrods. The colors were blue and black. Heathrow Airport T3 is a rather small store, but they do have wallets.
Thanks! Do you see any in GHW? I'll be heading to Sloane St. and Bond St. next Tuesday to try my luck!