Identify a Tree/Bush/Fruit

[cilben247]

I have a tree/bush in our garden but I want to know what it is, I have just found this fruit on it (there's only a few) but still don't know what it is. The tree/bush is about 9ft tall, it's actual thin trunk comes up about a foot and then breaks off into very long thin branches with little leaves on. Any help?

[WendyC]

What's inside? Is it a stone? Looks like a greengage or something in that family. What was the blossom like in the spring?

[Nicos]

I'd go with greengage too

[orangepippin]

I also think it is a Green Gage (as opposed to an unripe plum). The 2 most common would be Cambridge Gage or Old Green Gage, I'm drawn to the former although for no obvious reason.