Green Heron (Green-backed Heron) Butorides virescens
This beautiful little heron is an extremely rare visitor to the UK from North America. It's not been recorded in Norfolk yet, though it has made it to Humberside, Lincolnshire and Kent, so another east coast record has to be on the cards.
This species was formerly lumped as one species with Striated Heron, a species with a large world-wide distribution though absent from Europe and North America - collectively these were often known as Green-backed Heron.
The following individual was a popular and obliging bird that turned up in Cornwall.
Green Heron, Lost Gardens of Heligan (Cornwall, UK), 16th October 2010
This one was equally popular and showy, and had previously been seen in Ireland.
Green Heron, Red Wharf Bay (Anglesey, UK), 20th November 2005
And here are some from their normal range in North America: