This could be staining, but this adult winter Common Gull shows a clear light-apricot coloured wash on its body feathers. The bird drops in from the top left and lands momentarily in front and to the right of two white plumaged Common Gulls gulls. It then rapidly steals a crust and is gone. This series of photos, taken on the 6th December, shows a typical rapid feeding visit for most of the gulls that visit this Edinburgh garden.
Note, also, the bright bare part colouration of this gull with strong yellow tones in the legs and bill.