A very nice collection of 3893 Bumble bees
Ideal for anyone who wishes to hone their ID skills https://www.ispotnature.org/communities/uk-and-ireland/view/project/775454/ispot39s-bumble-bee-collection
I expect that anyone visiting this project will be aware of it, but this key:
http://www.nhm.ac.uk/research-curation/research/projects/bombus/key_british_colour_info.html
can be a useful starting point.
The key lists the 22-28 species it covers. I like the idea of a Small Earth humble bee.