What tree is this?

[doubleristretto]

I've tried spotter apps but not been convinced by the results. Please could you have a look at this? It self seeded and survived when the original plant died, I admire its tenacity and have nurtured it.

The catkin-y thing in the last photo looks a bit like willow but the leaves look rounder than willow ones. Hopefully a tree expert will be along soon.

Thank you for your help. Apps have Di far come up with box tree, monkey tree, donkey willow and grey willow. I'm not convinced with any!

Lilac tree?

Sorry, goat willow, I don't know why donkey popped into my head! How would I recognise lilac please?

Bay willow?

I’m guessing, but could it be bog myrtle, Myrica gale?

Thanks everyone! The jury's still out but pretty sure it's a willow of some sort. Without a definitive ID perhaps it's a new species...Donkey Willow it is!