Grumpy little mystery bird

I came across this strange little fledgling down by the canal. At first I thought it might be a young robin that had recently left the nest.

Then it turned its grumpy face to the front and showed a strongly speckled breast.

Clearly a fledgling - note wispy 'chick' feathers

This is mum (or dad) complete with a large caterpillar:

Mystery solved by the presence of attentive parents: they are song thrushes.

Common when I was growing up .... now only rarely seen. This will be their second brood of the year. Lots of juicy insects along the canal sides to feed the brood.