"Boche-Buster", a 250-ton 18-inch railway gun, Catterick, 12 December 1940. The gun later travelled down to Kent to take up position at Bishopsbourne on the Elham to Canterbury Line, taken over by the Army for the duration of WW2. The gun was in fact an 18 inch howitzer.
A fine view of the sheer scale and complexity of the big gun turret for a Battleship. In this case, this appears to be a British 15" gun mounting, of the type mounted on R class batlleships, "Queen Elizabeth" class and Renown and Repulse.