A lot of years ago - in the late nineties, I think - there was an odd Jackdaw that hung around Cley for several weeks. It was generally regarded as being '..of one of the eastern races'. I videoed the bird: it paired up with a more conventionally plumaged individual and, I seem to recall, built a nest on a chimney near the visitor centre. Looking at the video today, the Cley bird doesn't seem too different to the one in the photos below.
Now all Jackdaws in breeding fettle have a pale nape, but this individual that's been visiting my garden for a few days seems particularly well-marked.