...but a wind pump! These were used extensively across the Norfolk Broads to drain the marshy land and allow it to be claimed for farming and other uses. Now replaced by electric pumps to serve the same purpose, many of the older wind pump buildings are derelict or, like this one, converted to residential use.
What an interesting device - and an interesting use of words. Historically windmills have been used in Australia - to pump water up from underground reservoirs. But they have always just been called windmills. And they are no where near as decorative or complicated as this lovely specimen.
Super shot of this, you got the light just right. I have sailed past it before and always been at the wrong time of day for the light! Nice to see it like this.