I rather dislike the nickname 'White Nun' given to the adult male Smew - but then I generally dislike most of the nicknames birders give to birds. But you can't argue that they are impressive beasts. This party of four adult males and two 'redheads' (the females or immatures) were showing very obligingly near the perimeter road at Eye Brook Reservoir today.
Smew (Mergellus albellus)
Digiscoped with Nikon Coolpix 995 handheld to 20x eyepiece of Leica APO77