Coleson's Coppice (also called Calton's Coppice) was a 40 acre wood, previously part of Sydenham Common, bought by Thomas Calton from Henry VIII sometime after 1544. At about the same time Calton bought the Manor of Dulwich, which remained the property of the Calton family until 1605 when it was sold to Edward Alleyn. The wood was fenced, to keep livestock out, and the trees were regularly cut back to ground-level, to provide timber and encourage fresh growth.
The outline of the coppice is still apparent in this 1799 map, with what is now Honor Oak Road passing through the middle. Honor Oak Road, enters the common at what is now the junction with Westwood Park. The surviving White House and Hill House can be seen at the edge of the common:
The Manor House, built about 1815, survives as 53 Honor Oak Road, with considerable extensions to either side (some, I believe, by Ted Christmas). However, it's not quite that simple, for there was also another house, called Manor Lodge, near Canonbie Road. This was replaced in the 1930s by a house, called The Manor, that was demolished, I believe, some years ago.
The folly was built at the highest point of the garden of Tewkesbury Lodge in about 1880. Tewkesbury Lodge, south of Hamilton Lodge, was demolished in about 1930. The folly is listed grade II.
Much more information can be found in John Coulter's Sydenham and Forest Hill Past.