It isn't a "Churchill pound coin", it is a (Churchill) crown: five shillings (5/-), four to a pound.
The pound coins weren't introduced until quite a while after decimalisation in 1971 (when?) and led to the replacement of the pound note, a move that still hasn't been made successfully in the USA with the dollar bill!
And in answer to an earlier question about crowns (NB: the slang for these was a dollar, from when the exchange-rate was 4.03 dollars to the pound in the 1940s), they were still legal tender (IE: they could be used) but were actually only issued for 'ceremonial' purposes and, as such, collected.
Schaumburg, Illinois, U.S.A.