Challenge (W.F.C.)

The Challenge jig-saw puzzle branded box of my first known example carries the initials W.F.C. on the box lid, presumably referring to the manufacturer of these very uncommon puzzles. No country of origin is mentioned, but box and cutting style lead me towards a belief that they are of British origins and are thought to be of c1920's-1930's vintage.
Please let me know if you have any further examples.