Ugly duckling?

I nearly headed this: "Who am I?". OK, the shape strongly suggests that this is a partially fledged mallard. But when I first saw the bird it looked quite big, and I thought it was going to be a sleeping signet. Mallards are very sociable, but this bird was totally on its own, not another mallard within sight. S/he did come over towards the bank when I stopped, and that might be the giveaway.