I think you have probably got a Fieldfare in your garden.
They come over from Scandinavia in the winter I believe especially when we have bad weather, I suppose its worse where they usually live so they come over here for a while.
We always find a few in our garden and field each winter, eating the windfall apples.
They look like a large speckly thrush and bounce around a lot. They do scare the Blackbirds away , although this year, we only had one Field fare and loads of Blackbirds who soon sent him about his business.