Thanks to all for looking and kind comments; I really like this image.
This was taken at the Stourhead Estate in Wiltshire (Southern/Western UK) - a mostly 18th Century landscaped garden; The water in the image isn't a river, but a man-made lake, and I'd assume that the area that was flooded to make it in 1821 probably included Turner's Paddock, hence the name ... but I'm guessing.
Stourhead Garden is a honey-pot for amateur snappers, it's full of interesting views and architectural oddities, and the main garden also has a lake; the garden is planted throughout with specimen trees and so come autumn there are great cascades of colour cladding the small valleys and hillsides surrounding the lake.