I've said it before and I'll say it again - the buggers are all identical. Had one adult Herring Gull, one Lesser Black Backed, one second year Herring just starting to come into adult plumage and two indeterminate brown speckled things on the riverbed outside the Tower of London today. Going by size and the company they were keeping I'd mark them as Herrings, but plumage-wise it's an impossible task. Still, it's nice to see any adult gulls around at the moment, and it means the Passeriformes (read:House Sparrows) actually get a chance to scavenge. 2 Pied Wagtails rounded off the lunchtime nicely - I don't know why, but they always cheer me up.
Of course, my day was ruined when, on the way back, I happened across 2 Tower Pigeons shagging away on a low wall in the middle of a busy walkway. You probably have to have seen Tower Bridge Pigeons to get some idea of how stomach-turning this really is.
I have spent the afternoon erasing the image from my mind, and fully intend finishing the job tonight with the help of beer.