0,303" cartridge chargers with 'O' markings

This is a marking that I’ve wondered about for some time, it seems quite unlike the initials that are generally used to denote the producers of most UK made 0,303" chargers, seeming to be more of a symbol. Thus far I’ve seen it on MkIII and MkIV* chargers.

At the recent ECRA meeting in the Netherlands there were quite a few of the later MkIV* chargers for sale, might they be produced in Holland? Any suggestions gratefully accepted.

Happy collecting,


edited once; grievous inattention to syntax