In 2018 site work in Cape Town revealed a 9.2-inch disappearing gun position built by the British in Battery Crescent, Seapoint, Cape Town. The mountings for the gun appear to largely be on site, the pit having been back filled. The location is now protected with the intention of turning it into a museum by 2020.
Note images on this plot from BBC (British Broadcasting Corporation).
The National Archives, WO 78/4941