Bullfinch, common in garden or not.

     I saw this bullfinch in our garden yesterday, feeding on sunflower hearts. It fed for a short while then kept flying into our thick laurel bushes and returning to feed again. It's the first time in nearly 20 years that I've seen one in the garden and I was wondering if they are a fairly common garden bird.  Also, what is their normal food? We live near the edge of Durham city and there's woodland within a half mile or so.