You can try this yourself. The NHM has an identification guide for bumble bees.
I used the flash version. For the thorax it doesn't offer an orange/black/orange option (as it appears in your photo) but there is a yellow/black/yellow which I tried. The abdomen seems to be all black so I selected that and it suggested ruderatus. However, you saw the bee and you may have other information not in the photo.
Is the tip of the tail white? If so it is possibly a Tree bumblebee (Bombus hypnorum) - we have a colony of bees with the same pattern of colours in our roof at this very moment in time so would be keen to find out if I am correct in my ID too!
I think the Tree Bumble Bee is a definite option as the very tip of the tail was white. The B. hypnorum I have seen round here are normally a lot smaller than this fellow. The fur on the thorax seemed very choclate brown in the flesh and perhaps the side view could be a little misleading as it was a very dark photograph and I have lightened it a tad.
It is definately not B.campestris, which is a cuckoo bee, so doesn't collect pollen. If you look at the enlarged view of the top photo, you can see the 'pollen basket' - a broad flattish shiny area with long hairs on either side -and at the joint between the two biggest sections of the back leg you can even see the 'pollen press 'which helps to push the pollen upwards into the basket.
I think she looks like a queen B.hypnorum with a slightly worn dark area on top of the thorax.
There is lots of info about hypnorum on the BWARS web site.