ooh that is intriguing. I don't recognise it. Is it woody? looks like it might be.

It looks so much like Magnolia Stellata but in the UK, it wouldn't have flowers and leaves at the same time.

I think it probably is a native. But I would love to know what it is.

Yes I think it could well be, the flowers and leaves look right, a self sown gift from the birds perhaps. I had thought it was a nature's gift with it where it was growing.

It is also a native and produces berries.

rhs link for more info if you are interested.

https://www.rhs.org.uk/plants/1059/i-amelanchier-arborea-i/details

I would say Amelanchier too.

Amelanchier alnifolia has flowers and leaves at the same time so I reckon that's it.

The leaves look like Alder too so that name alnifolia would fit nicely.