Webley-branded (prototype?) pellet holders

Webley-branded (prototype?) pellet holders 

With thanks to Phil. He says:

I purchased these some years ago from someone whose name is now lost to time that had once worked for Webley. He told me x4 were made x2 in .22 and x2 in .177   He told me they were prototypes that never made it into production and although I have no proof.