The picture is from and is a link to the 'Brightling, East Sussex - village website', if you click the picture you can see the original document this comes from.
The building was constructed in 1803 and was the first folly created by John(Mad Jack) Fuller. It is a brick structure coated in Coade stone to make it look like real stone, but was significantly cheaper, and more flexible when constructing buildings.
The Coade stone itself was made of a durable weather-impervious ceramic that was cheaper than real stone, which was made of clay from Lyme Regis, mixed with fine ground pre-fired clay, sand and ground glass. It was developed by Eleanor Coade in 1769 and the Coade's Artificial Stone Manufactory produced monuments and other forms of sculpture, and still today there are more than 650 examples of the use of this material.
The summerhouse is likely to have been created as a standard design from one of the Coade catalogues produced between 1769 and 1820, as individual designs would have needed their own moulds and would have been very expensive.
Please be aware the Coade Summerhouse is on private property and there is no public access.
Other Reading
If you would like further details of Mad Jack, the Fullers or the Brightling area please click on the following links: