There's rooks, crows and jackdaws around here, and it gets pretty easy to tell them apart. Rooks are slightly bigger than crows and have a thicker, bigger beak (often with the lighter bit near the head). Jackdaws are slightly smaller than crows, and they have this silver-grey top and back of the head

Anyway, I'm pretty sure I shot a took, here. I'll see if I can confirm with a colleague, who is a massive birder, but I'm already pretty confident.

Edit: my confidence was, alas, unfounded, my photo was of a carrion crow.