Is that a dunnock?

Hi

I'm new to this blog, have registered for big garden watch but am unsure of the identity of our little garden visitor. It could be a dunnock, looks like a smaller robin with a silvery chest instead, has very little patterns on her back that are characteristics of a dunnock. Someone told me it might be a silver breast??!!

It comes every winter with a fellow robin and can be found on the ground as well as inside our bird feeder; very shy.

Would appreciate any ideas. H