WW2 coastal lookout?

I'm not entirely sure that my description of this is correct, I'm sure someone out there will be able to help. I have googled this building between Tayinloan and Clachan and other photographers have described it as a WW2 coastal look out point. Anyway, whatever it is gave us a good walk on Saturday along the beach from Tayinloan.
Back blip again due to no internet at Castle Sween.
Friday's Backblip can be seen here