Hi BigDuke,
That's really useful info thank you very much. I was envisioning some kind of nightmare scenario, of splitting them with razor blades or something, I'm breathing a big shy of relief.
I refer to these as small, as they are considerably smaller than the regular no5 or mk5 that went onto great wartime success. They do have independant focusing, and were only made in 1936, approved and cancelled on the same day. They are a lovely set of Bino's thou just mini regular No 5's, even smaller than the fixed focus aircraft mk5's, must admit it gets very confusing with all the 5's being thrown around, thanks again.

Regards Ian