Could it be a juvenile robin? I believe they look like extra large sparrows, and are browns without the red chest while they are young
Is it possibly a dunnock, also known as a hedge sparrow?
Central Norfolk UK
edited February 2021
Young robins have speckled brown breasts, but the red breast has usually appeared by autumn, after the bird’s first moult.
“I am not lost, for I know where I am. But however, where I am may be lost.”
Winnie the Pooh