Battersea Park: Black East Indian Duck?

Glossier in large

Back from Bristol and Bath; I'll back blip in due course...
Im and I went to Battersea Park in the early afternoon; spotted a storm-felled hybrid strawberry tree which was dramatic, and otherwise just pottered around the lakes seeing who we could see. This v. pretty iridescent domestic duck (Black East Indian?) was gadding about with another similar one and a mallard-looking call duck-ish drake; my camera battery ran out (!), so I didn't get many shots of them, but this one showed off the glossiness quite well.

Others here (or right from Swan flapping)