I saw this bird on my garden wall in Twickenham on 8 May around 10 am. I wondered if it was wounded as it wasn't moving and was being attacked by two crows who live in one of the trees. But when I opened the back door it flew off. There are no ponds around here although the Thames isn't far away. I have never seen anything similar in the garden before. I assume it is a heron, is it any paticular kind of heron?