I caught a glimpse of this bird last week when the hawfinch was here, but afterwards thought I might have imagined it.  It turned up again this morning while I was on the phone, so I got a couple of quick shots from which I've identified it as a ring ouzel.  I'll be watching for it now to try to get a clearer picture...this came out better than expected considering I took it one-handed with a zoom while talking on the phone...perhaps I should adopt this as my technique going forward ;)