No, not native, though there are a fair few feral ones around as it is a very popular bird in wildfowl collections/aviculture (you can see why!). It has bred in the wild in the UK but not enough yet for it to be considered fully established and self-sustaining.
My blog: http://mazzaswildside.blogspot.co.uk/
My Flickr page: https://www.flickr.com/photos/124028194@N04/