White-tailed bumblebee  (Bombus lucorum)

English Nature's 'Help save the bumblebee' leaflet is available at:
http://www.english-nature.org.uk/news/news_photo/savegardenbumblesweb.pdf

For more on bumblebees see: Prys-Jones, O.E. & Corbet, S. A (1987). Bumblebees. Cambridge University Press, Cambridge.