Thanks for that info Ronnie.
Green uv reaction under longwave uv is consistent with all of 1930s Ysart, Ysart Brothers (Vasart), Vasart Ltd & Strathearn Glass. All of the "unknown maker" items I have checked with uv do not show a Green reaction.
So although I see some features that are perhaps inconsistent with usual Salvdor Ysart style inkwells I have seen, I am happy to say it is not from the "unknown maker" range.
Whether it was made by Salvador or one of the sons (but not Paul), or somebody else in the later Vasart Ltd period or even in the Strathearn years will probably remain a mystery.