The QF 4 inch Mk XVI gun was the standard British Commonwealth naval anti-aircraft and dual-purpose gun of World War II.
Twin Mk XVI on HMCS Haida
Crew of a dual 4-inch at action stations aboard HMS Berwick while in screening the Atlantic Convoys in May 1943.
Twin guns of HMAS Swan bombarding shore positions in New Guinea, February 1945
Single Mk XX mounting on HMAS Barcoo, 1945
HMS Activity was an escort carrier that served with the Royal Navy of the United Kingdom during the Second World War. After the war, she was sold into merchant service as the MV Breconshire, serving for over 20 years until scrapped in 1967.
HMS Activity underway in the Firth of Forth, October 1942.