Kindlekitten, there's a link to the RSPB site
here. I think it's slightly different to the photo you posted - but I must admit, I'm determined to make the most of the sunshine so I'm sitting outside and squinting at my screen here, and can't see much of anything. It's definitely part of the magpie/crow family, though. I thought it was quite exotic when I first saw it (or its forebear) a few years ago - til it opened its beak and squawked.
Apparently the Latin name is garrulus glandarius.