I now have a couple of photos that should help identification. Unfortunately it is not possible to get a whole tree picture as the tree is part of a hedge and if I step too far back I'd end up in the canal. The leaves are smooth underneath. I hope this helps because you can just about see fruit in the first pic
Your tree is a cherry. The leaves in your original photo show the characteristic blunt and uneven teeth of wild and morello cherries and in the later photos you can see the ripening fruits. Since the leaves are smooth underneath, it is likely to be a morello cherry. If you decide to taste the fruits, take care - morello cherries are not eaten raw and can be mouth-puckeringly tart (the alternative name is sour cherry)! Even those of wild cherry trees (from which dessert cherries are derived) are not always sweet. It would be better to visit your local market.
Hi team, thanks for the information. If I can reach enough then these cherries are destined to become Cherry Brandy (from "Food for Free" by Richard Mabey) or jam with enough sugar to conquer any tartness.
I have already added these trees onto the interactive map.