Bewick's Swan Cygnus columbianus bewickii
The Eurasian race of Tundra Swan - a declining winter visitor here in Norfolk. I don't seem to have any photos of the nominate American race (sometimes known as Whistling Swan, though in America more commonly just as Tundra Swan) although I have seen it both in Canada and in Scotland (a vagrant here although that individual was widely touted as an escapee).
Bewick's Swans, Welney (Norfolk, UK), 4th February 2017
Bewick's Swans, East Wretham Heath (Norfolk, UK), 21st January 2017
Bewick's Swan, St Benet's Level (Norfolk, UK), 23rd January 2005
first-winter Bewick's Swans (with adult Whooper Swan), Stanhoe (Norfolk, UK), 14th February 2007
Bewick's Swan, Welney (Norfolk, UK), 9th April 2011
Bewick's Swan, Ranworth Broad (Norfolk, UK), 17th December 2011
Bewick's Swans, Catfield (Norfolk, UK), 23rd January 2005
Bewick's Swan, Narford Lake (Norfolk, UK), 20th January 2017