The Dunnock, also called the Hedge Sparrow though it is not a sparrow but an "accentor", has pretty rich brown markings on its back like a sparrow. It is a common bird but hides and skulks in undergrowth. The female Dunnock (left above/below) is a little more streaky than the male in his breeding plumage, the latter having a plainer grey head and chest (see right above/below).
Dunnocks often live in groups of 3-4 rather than pairs, especially 2 males and one female.
The Dunnock is a similar size to the Robin
She often has her tail to one side in the spring
This Dunnock had only one leg. Despite it's disability, the bird seemed to carry out a normal existence.