A case of confusing identity

I had taken my 200mm telephoto lens out with me intent on shooting some sea birds. Whilst I was sitting on a bench looking out on to the beach, this rook alighted on the sea wall just a couple of meters away. Its was almost too close for telephoto lens to focus.. As he was quite happy to perch there, despite the fact I had two dogs with me, I took a number of frame filing shots of him. Unfortunately there were some grasses around that tended to obscure the view but not so much that I was unable to photograph his plumage. I am assuming it is a rook and not a crow as I know they can be very similar. There is however, a rookery in the trees behind my house as the birds there are clearly very sociable and I suspect that he/she came from there.

Worth seeing LARGE t take a close look at the plumage