Confidence: It might be this.
Notes: Large / Bombus / 25mm.
Walked out of a nest of Bombus terrestris. Workers not seen at nest for several days then I observed 4 of these large bees leave the nest on 13/8/13 and 2 more leaving the nest on 14/8/13. all on foot. No more activity at nest since. Thought they may be B.vestalis