What a coincidence Keith. Don't remember seeing another, but probably more common than we think.
Presumably it's the coloured examples that David is referring to when he says made in clear and 'opaline'. You've probably seen the blue example in Charles Hajdamach's book which carry Churchill's epitaph to the 'few' - are they very rare do you know?
Mine doesn't have any of the othere marks that David speaks of i.e. 'Parker' or 'Fibreglass' - they apparently also did one (presumably pre-war) containing uranium.
You can have this one for nothing if you want a blue one.
