i’d say a tree bee - wads of them about this year in my garden.
I’d initially thought Tree Bee, but none of the identification pictures has the hole in the ginger thorax. Thanks for helping.
Your friend has a nest of Tree Bumblebees - Bombus hypnorum. The “hole” on the thorax is just fair wear and tear for a bumble that has been around for a while - they don’t stay pristine for ever, just to match the i/d charts. The ginger hairs have worn away showing the black cuticle underneath. Now that the new queens and drones are on the wing, the nest should begin to break down and all but the newly mated queens will eventually die off by autumn. My nest box tree bumbles are still active around the garden but I’m now finding one or two dead ones on the ground.
Your description with photos of the ginger thorax is very interesting. I have never noticed this feature on the tree bees I have seen but the illustration in my field guide –Edwards and Jenner - does show a distinct dark patch in the centre of the ginger thorax. I think the clearly defined white tail combined with a ginger thorax is a pretty convincing indication of the tree bee (male or female).
Have you thought of sending the photos to the Beewatch website -
where you can upload photos for identification?