Maker zZz on WW1 era British fuzes?

[Darkman]

Can anyone identify the maker zZz on these British fuzes - No. 94 and No. 83 converted to 81?
Z in a circle was the American Yale lock Co (Yale & Towne), but never seen zZz before.

Thanks

 

[MINENAZ16]

same question for my 83 converted 94 :

 

[Darkman]

Any ideas on the zZz ......... or is it all zzzzzzzzzzzz?