My guess would be some kind of cherry tree with flower buds. I can't see any ivy?

Steragram - thank you for your reply. I thought so too but these green things look mossy and somewhere between a bud and a berry - rather confusing. The ivy is covering the base and trunk of the tree, these photos were from the top branches. It’s a very tall tree, possibly around 15-20 feet.

I would suggest something like Bird Cherry.

Strange isn't it? I've just been out to look at flower buds on a cherry grown from a pip - not a bird cherry - and the flower buds don't look much like yours. I was judging by the bark of the tree and relying on memory for the flower buds.. Would be interested to see what happens in a week or two if its not too much trouble! Bulba wouldn't bird cherry buds be on a longer stem rather than a tight cluster?

Hard to tell with all the leaves off, but the branching pattern reminds me of some species of Pistacia. If so, these would be the emerging male flowers. Nothing spectacular even when fully open, but weird looking at any stage.

Steragram - I’ve updated the question with the latest photo of the tree and the second two photos are pre-flowering. I couldn’t post the photo in the followup comment. It’s such a pleasant surprise ! Beautiful tree!