I've had a pretty successful time just recently tracking down difficult birds. The Chough was another one of those birds. They aren't in many parts of the UK, but a few times I've missed out somehow, even when making a concerted effort to go and find them.
At South Stack on the island of Anglesey, these birds breed and my luck was in. I only had a few minutes watching them, but it was better than nothing. Love the red legs and bill.