Unidentified Flying Object

I have seen this little duck several times now, up and down the Leeds-Liverpool canal around Saltaire. I haven't a clue what sort it is. It's certainly not a familiar British duck so I can only conclude that it's an 'escape' from a park or collection of waterbirds. It's very pretty, with a small, attractive head and unusual mottled plumage. Its beak is dark and rather small. It hangs around with the mallards and seems to have started to believe it is one! It wasn't in the least afraid of me, and let me get quite close to take its photo, which may be another reason to think it has escaped from a collection where the birds are used to human contact. Anyway, if anyone has lost it, I last saw it near Hirst Mill swing bridge.