on right, with black-headed gull on left.
No interactions present.
Mark at Magdalen is correct with respect to te bird on the left!
the text of the posting made clear which bird it was that the original poster wished to identify.
Sorry your right, the original poster did make it clear that it was the right hand bird to be identified and its also clear that this bird is a first winter Common Gull.
Lat/Lng: 51.5875, -0.1186
OS grid ref: TQ304893