sam - ack-ack gun

An example of a 3.7inch anti-aircraft gun [very incomplete, I have to say] that was mounted on the Maunsell Fort in the Thames estuary.

This type of weapon was the primary AA gun for Britain in WW2, it came in mobile or fixed versions, and a grouping of guns - a battery - usually had between 6 and 12 guns. Some batteries had female gunners and included spotters, searchlights etc ...

Production of these guns started in 1937, primarily by Vickers.