David had picked out a 1stW male Caspian Gull feeding in the harbour at low tide. By the time I arrived, the light was already beginning to go but I took a series of pictures on a high ISO although hopefully David will have better when he digiscoped it in better light before I arrived.
It was picking up mussels out of the sea and was quite aggressive to the other large gulls nearby.
 
albatross posture
 
 
long-legs
 
 
diamond shape marking on the scapulars.
 
1stW Caspian Gull at Newhaven Harbour.
(Last 3 images digiscoped by DC)
For DC's comments please see: 
http://eastsussexbirding.blogspot.co.uk/