HMS Conway Wrecked on the Menai Straits, & Artillery Manouvres, Wales, 1953, filmed by Fred Pedley

[@thepumpdoctor1]

Tight squeeze for the big guns! Good job the officer is there to help. My guess is a BL5.5 or 7.2" gun.
en.wikipedia.org/wiki/BL_7.2-inch_howitzer