I just bought this 2011 Great Britain proof WWF (World Wildlife Fund) 50 pence copper-nickel coin off Ebay. Mainly for the 2 "bugs" on the coin for my "Coins with Insects" coin collection. KM#1196. I am not sure of the mintage number ???
https://onlinecoin.club/Coins/Country/United_Kingdom/Fifty_Pence_2011_WWF/ Basically 3.5 mil mintage (3.4 mil circulated, 96,273 other)
Numista has the mintage broken down differently, so who knows https://en.numista.com/catalogue/pieces27054.html
From My Krause world coin catalog I see that they only have a proof version of the .925 silver version no UNC. version.