Can ayone help identify this tree?

[kimandkelly]

This tree has been in our garden since we moved in about 3 years ago, normally the birds eat the fruit but this year it is full and the birds seem to be ignoring it. We think it is a type of cherry but they seem quite sour and I would like confirmation before cooking them. I really don't want to poison my family but it seems a shame to waste them.
It has white flowers in spring.

[veggiechicken]

Welcome Kim and Kelly
Could it be a Morello cherry? Morello cherry trees for sale | Buy online | Friendly advice. If not, maybe a Bird Cherry?

[FB.]

Looks like a cherry of some sort, but the small and quite intensely coloured fruit (most cherries seem to be more maroon to black in colour) makes me wonder if it's more of an ornamental than a tasty, productive variety.

edit: if that's its large trunk in the background, it's either on a very vigorous rootstock or it might have been grown from a pip/seed and therefore not be able to be identified. It is quite common for seedlings of any fruit to be inferior to their parents.

Is there any evidence of a graft?
Grafts are usually a few inches from the ground level (although ground levels can change over many years).
However, I have seen some cherries in Cambs grafted at a height of around 6ft off the ground - perhaps "stem-building" a weak-growing variety, or perhaps "inter-stock" to boost vigour of a weak-growing variety.

[KittyColdNose]

I thought bird cherry as well VC.