Lesser Black Backed Gull (Larus fuscus)
The Lesser Black-backed is not an uncommon species in winter around our shores, and it is always worth having a closer look at any gull with a dark back to see if it is 'Lesser' rather than 'Greater'.
As you might expect, the Lesser is smaller than the Greater but also the Lesser's back is less black than the Greater's!
The Lesser Black-backed Gull is a very close relative of the Herring Gull, it is the same size, has similar legs and beak (including the red patch) and in many ways is just a Herring Gull with a dark back.
In the south of England the Herring Gull is much more common but as you head north so the Lesser Black-back takes over.