Amazing Mallard?

At around 4.30 today after a days on and off Osprey watching a beautiful duck flew onto the reserve. I could not at first identify it as it had really bright white wing tips and a white underside and ring around its neck I expected to see a Goosander or something like that but the camera shots seem to show it may be a Mallard with a incredible variant in its colouring. Pictures on the photo section.