Carrion Crow
Corvus corone

The Carrion Crow has recently been split from the closely related Hooded Crow and now are both separate species, both of which occur in Britain. They're intelligent, loud creatures and can form roosts of hundreds of birds. Photos 1 and 3 are adults and 2 is a juvenile, as can be seen from the slight yellow at the corner of the shorter beak.
 

See the painting of photo 3 here.

1: Radipole Lake RSPB, 23/01/2007.
2: Dawlish Warren, Devon, 19/06/2006.
3: Gartloch Pool, Nr Glasgow, 10/07/2005.