This is not exactly an ID question, but still...
My wife was on a visit to Oxfordshire (a rural location a few miles from Banbury) and she saw what she can only think was a Raven. While she is not an expert birder, she does know a Carrion Crow, a Rook and a Buzzard when she sees one, and she says it was much bigger than either of the first, and about the size of a Buzzard, but more massive. She described the beak as having a 'humped' appearance.
It was sitting on a fence post about 50 - 60 feet from her, so she had a reasonable look at it.
She lived in that area for many years, and is still a regular visitor, and she says she has never seen a bird like this before. It would seem that the only possible option is a Raven, but are they known from the area?