The Duke and Duchess of Boxford had a summer house built when they came on their second visit to the Island of Sodor. However, four years later, Spencer came back to Sodor to build a new summer house for them. But, due to Spencer being suspicious about Thomas, this summer house was nowhere near completion when his owners arrived for their holidays. However, thanks to Thomas, Spencer and Hiro, the new summer house was completed.
The summer house was originally situated close to a railway siding, whilst the new summer house is situated alongside Edward's Branch Line. The new summer house was rebuilt on the Ulfstead Branch Line. It is unknown what became of the original summer house.
The summer house was first introduced in the eighth season episode Edward the Great and then the new version was under construction in Hero of the Rails. Since the CGI switchover, the new summer house appears to be located at Boxford.