Oh, and a trio of Red-breasted Merganser. Merganser are fish-eating ducks, diving saw-tooths with long, slender, serrated bills. Of all the ducks, they have the most of the dinosaur about them. The light was not good, they were skittish, and feeding on the far side of the Thames. But they looked much like these. The male has a bright raggedy green iridescent head; the female is a sparky redhead.
Inland and south isn't their natural home; more likely to see them on the Scottish coast, or in lakes. I worried briefly that they were escapees from a collection. Ornamentals are often kept in threes to increase the chance of breeding. But then they spotted me and flew downriver; definitely wild. Tourist ducks.