unfamiliar bee

unfamiliar bee

Observation - unfamiliar bee. Description: We netted this bee from our small corkscrew willow tree in our back garden as it appeared to be a bit of a beast and seemed odd that it kept returning to the same branch in the tree. Approx 3-4 cms long, dark with yellow/orange fuzz though not particular

We netted this bee from our small corkscrew willow tree in our back garden as it appeared to be a bit of a beast and seemed odd that it kept returning to the same branch in the tree. Approx 3-4 cms long, dark with yellow/orange fuzz though not particularly hairy. 2 pairs of wings that appeared longer than the body and very chunky legs. Big black eyes to the front and antennae with knobbly bits at the end.
Once we'd snapped our pics and let it go, it went back to the willow, where it would land for 10-15 min then fly in a few large circles around the top of the tree and go back to same few branches. It did this for about 3 hours at least. Any one know what this could be and if it is likely to be a queen- will we end up with a swarm? Or why it liked our willow?
We couldn't find it on any ID sites this afternoon.
Thanks