Identification of Plant/Tree

ATKI starts with ...
Hi There,
We have been trying to identify this plant in our front yard. The fruit when it is raw looks like olive. However, when it ripes it looks like plum. Should be happy about it however, it is growing like a weed in our front yard. it does not grow through the seeds but through the roots. The plant grows from the roots which spread horizontally just a few cms below the ground level at different points, mean to take it off, i need to dig to the roots.
You will see an off shoot after about a metre. thus, making garden inaccessible to us. the mature tree is about 2-3m tall. I am attaching some pictures hope you guys can help me out.

Pictures - Click to enlarge
Picture: 1	Picture: 2	Picture: 3

John Mc says...
Pics would be good

speedy says...
Looks like a Prunus sp.
some kind of European Plum.
maybe it's and old rootstock that's gone mad with suckers long after the scion has died, or a seedling.
I was thinking maybe a blackthorn- sloe (P.spinosa), but now I've seen the pics, it's not that.

Julie says...
It has never fruited amanda. Maybe it needs the greengage as pollinator?