The drake Mandarin (Aix galericulata) really deserves to be illustrated in colour but even in monochrome its exuberant plumage is apparent. While this duck is native to the Far East, it has a self-sustaining breeding population in the British Isles (category C1E in the BOU's British List). It is closely related to the Wood Duck or Carolina Duck (Aix sponsa) from North America but I think the resplendent plumage of the Mandarin beats it with the crazy 'wing sails'.
This drawing took me a lot longer than usual as the whisker-like feathers of the cheeks were tricky to get right. Click it for a larger version.