I had not seen this bee in the garden until a couple of days ago. The colour is black and silver. Silver/grey on the thorax and silver stripes on the abdomen.
No interactions present.
This is a male of either Bombus bohemicus or Bombus vestalis it is very hard to tell the difference between them from a photo also one tends to be north of roughly Bristol to the Wash and the other south of that line .. they are both cuckoo types of bees and the colour of you be is just faded
I have added a revised ID re this bee, I don't know if you will agree, but all comments are welcome. This a parasite of the Spring Flower Bee which in season(late this year) always comes to the garden.
No it is most certainly what I stated the only reason i couldn't put for certain because its one of the bees that you really need to photo from every angle or even see up close to determine which type it is either the northern or southern version .. all it is the photo shows a bee that has faded all bees as they go through the season fade and loose hair this bee has a squared of abdomen where as the cuckoo bee you have put up has a rounded end... also one of the id points for what I said is the broken faded yellow line above the white which is the classic sign of both of the bees I stated.
but im sure someone else agree with one of the Ids also take alook at the rest of these http://www.ispot.org.uk/species_dictionary/Bombus%20(Psithyrus)%20bohemicus
kind regards stephen
Lat/Lng: 51.9, 0.9
OS grid ref: TM0127