It's a Willow tree. I think Goat, but might be Grey or even a hybrid!
Thanks Gareth, appreciated. I thought it may be some type of Willow but was unsure. Cheers
Also known as Sallow (Great Sallow for Goat Willow, Common Sallow for Grey Willow) - they're very similar, best way to tell them apart is the leaf shape (but too early for that). The male catkins are an important early source of pollen for queen bumblebees. I passed the same bush on friday evening, it was still humming!