Having trouble identifying this bird

Was by itself amongst a group of mallards and swans (and gulls obviously) 

.Any help would be much appreciated, thank you

  • I would think it is a feral mallard hybrid. There are so many types, they have the generic term manky mallards and a few are iridescent green/green-black all over, similar to the head of a wild mallard male

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    Nige   Flickr

  • Looks like a domestic breed to me, I believe it may be a Cayuga. This breed gets its name from Lake Cayuga, just west of New York, America. They were bred from the wild Black Duck and Rouen. They arrived in the UK when they were shown at the Great Exhibition at Crystal Palace in 1851, according to the info I found.