There are several newspaper reports of this being a Standby Headquarters for Strathclyde Regional Council. It is a windowless surface bunker. “built by the MOD in 1940-3 as a telecommunication centre for all three services. Its walls are four foot thick!” - but no building visible on 1947 or 1949 APs so must have been built around 1950. Now used as a Crosslet Community Centre.
Lennox Herald - Friday 18 September 1987 New bunker in event of nuclear war
Lennox Herald - Friday 26 May 1989 NEW LIFE FOR DEFENCE BUNKER
West Dunbartonshire Council World War II Military Installations
[Google Maps]([Crosslet Centre](https://www.google.com/maps/place/The+Crosslet+Centre/@55.9450939,-4.5466957,3a,75y,191.54h,77.8t/data=!3m6!1e1!3m4!1skHBtkU71fjLv4J0SjiJe4A!2e0!7i16384!8i8192!4m7!3m6!1s0x48885283309909b3:0x53c87b4bd4a5c4de!8m2!3d55.94499!4d-4.5467801!10e5!16s%2Fg%2F1ypmn43qw?authuser=0&entry=ttuCrosslet Centre))