Re: the mystery green plum ...
I just copied this from a website Toffee...
Compared to the attractive colouring of most plums, the appearance of Old Green Gage fruit is fairly plain - the plums are quite small and a dull green colour, turning slightly yellow when ripe. However this is one that you grow for flavour - for eating fresh it is exceptional.
It didnt say wether they had a pip inside them though