Dunnock
Prunella modularis

Dunnocks are also sometimes known as Hedge Sparrows or Hedge Accentors. The latter is correct, but the former is wrong as they are not sparrows, but accentors. They are the only native accentor to Britain (there are thirteen species in total). The plumage is similar to a House Sparrow, except for the lead grey around the head and neck.
 

1: Bowling Green Marsh RSPB, 01/12/2006.
2 and 3: Chard Reservoir, 03/03/2007.