Yesterday I saw this faded bee feeding on a thistle flower and took a photograph thinking how good it would be show how faded bees become at this time of year. It was only when I uploaded the photo that I realised it had only one yellow band (almost white now at the end of the season) and this sent me looking for my identification guide.
It is cuckoo bumble bee, not a true bumble. As the name suggests the cuckoo bumble bees lay their eggs in bumblebee nests and then leave them for the bumblebees to take care of. The cuckoo bumbles often have similar banding patterns to their hosts.
The host species of the Forest Cuckoo bee, Bombus sylvestris is the Early Bumblebee Bombus pratorum.