I have been investigating how the Mandarin's 'sails' are constructed. The Birds of the Western Paleartic e-edition (the avian equivalent of the indispensable Hitchhikers Guide to the Galaxy and Nigella Lawson's Simply Nigella) explains that they are extended tertiary feathers. Mainly orange-chestnut but with a blue and black edge. There is a great picture of the feathers on the following site.
There is a large breeding population in south-east England, and smaller ones elsewhere but the Aeron bird has a red ring so is doubtless an escape.
I don't know if anyone watched David Attenborough's Great Barrier Reef but in the second episode there was a sequence showing wedge tailed shearwaters found in islands off Australia. They showed them landing and commented that they were more awkward on land but they were definitely better 'scuttlers' than our Manx shearwaters.