I found this occupied Ash Tree by the river. The bees aren't very dark but it was quite an active colony. Amazing amount of Himalyan Balsam along the river banks, covered in mainly bumble bees.
The bees are located in the vertical slit at the base of the tree. The tree is located in open marshy field. There are at least 3 other free living colonies in this farm.
16 Sept 2020
Total reported by Simon is 4