I would say this is a 1st year Slaty-backed, a rather faded individual for midwinter. The relatively short primary projection, the uniform (though pale) greater coverts, the darker belly contrasting with the pale head and chest and the pale fringes to brown primaries indicate this. The bill is rather pale, though this is a highly variable species. I can't see anything in this bird to suggest hybrid origin, although I don't have much experience of such birds. However, I'm pretty certain it wouldn't be an F1 hybrid.
GeoffC
