Dryden Tower.

This folly was built in the mid 19th century in the grounds of the now demolished Dryden House owned by the Lockharts of Carnwath. Most of the land belonging to the estate is now buried under the spoils of Bilston Glen Colliery, while deep underneath are the mine workings that were abandoned in 1989 after the flooding that followed the miner's strike. It is a sandstone Gothic building apparently undergoing preservation at the moment; I have never known it not fenced of due to it being in a dangerous condition. No one seems to have noticed the scaffolding going up, so we don't know when that happened. It is variously described as being in Roslin, Bilston and Loanhead but, being on Langhill Farm which is definitely in Roslin (unless someone bigger than me wants to argue bout it), I claim it for Roslin.

So there you have it, my brief searches have failed to find any useful information about the building, but I will be watching for developments and trying to find out more about its history.