On the offhand that this image is a folly, I contacted The Folly Fellowship and asked if anyone knew what it was. In no time at all, two of their members identified it and one posted a source print on the Folly Fanciers Facebook page. So here is the url for a picture of my plate and the source print. The pattern is "the Fishing Temple at Virginia Water in Surrey."
https://www.flickr.com/photos/80103401@N08/ The gentleman who identified the folly is Garth Hughes and he included this link to the history of the building.
http://virginiawater.co.uk/scr/histlist.php?locid=&bid=16 Unfortunately it was demolished in 1936.