From the 20th Philatelic Congress, London 1933. Seven different paper types, all depicting a top-hatted postman. (Seven colors, too.)
[edit: De La Rue printed them...I wonder if londonbus hasn't shown them here before? I thought I had a scan, but I must have thought up a clever name...]
[here...are these the stamps?...
https://goscf.com/t/7600 ]