Probably no weapon is more representative of the great era of British battleships than the 15-inch gun. Designed in the days when modern naval gunnery was still in its early stages, the 15-inch gun was finally directed by extremely sophisticated fire control techniques. The battleships and battle-cruisers that mounted these great guns, two in each turret, were the final arbiters of sea-power. Each floating steel castle was screened by cruisers, escorted by destroyers, guarded by mine-sweepers, covered by aircraft, fed by auxiliaries, and hunted by torpedo craft. When all the skirmishing by lesser vessels was done, it was the nation which still had the most battleships afloat that controlled the seas. This was the meaning behind the Battles of Jutland, Narvik, Calabria, Spartivento and Matapan, the Bismarck action and the surrenders of the German High Seas Fleet in 1918 and the Italian battlefleet in 1943.

Yet although the 15-inch gun was built for sea-fights between opposing battlefleets, its first action was bombarding shore positions at Gallipoli in 1915. Thirty years and two major reconstructions later, the same Queen Elizabeth was providing heavy artillery support in the Indian Ocean. In two world wars 15-inch guns bombarded the coasts of France, Belgium, Holland, Italy, Africa and Madagascar, supporting Allied troops on the beaches, wrecking enemy installations and thwarting a hostile invasion of our shores.

Twenty-two ships of the Royal Navy were armed with 15-inch guns: Abercrombie, Barham, Courageous, Erebus, Glorious, Hood, Malaya, Marshal Ney, Marshal Soult, Queen Elizabeth, Ramilles, Renown, Repulse, Resolution, Revenge, Roberts, Royal Oak, Royal Sovereign, Terror, Valiant, Vanguard and Warspite.

The 15-inch gun was not cast in one piece, but was built up as a series of tubes. These tubes were heated until they expanded and were then shrunk over each other. The centre tube was known as the Inner A Tube. It was replaced when the 76-groove rifling was worn. Then came the A Tube, around which 170 miles of wire were wound. Over that was fitted the B Tube, which, together with the Jacket, formed the visible exterior of the gun.

The left-hand gun (Gunbody No. 125) of the pair situated outside Imperial War Museum London was made by William Beardmore and mounted in HMS Ramillies in 1916. It was first fired in action against Turkish shore targets during operations in the Sea of Marmara in 1920. Apart from practice shoots, it was not fired again until 17 August 1940, when when a British force bombarded Bardia in North Africa. HMS Ramillies also fired several salvoes during the Battle of Spartivento in 27 November 1940. The Italian warships were out of range and no hits were scored. The gun was removed from HMS Ramillies in 1941 and stored. The tampion badge is taken from the arms of the Duke of Marlborough, and translates as 'Faithful but Unfortunate'.

The right-hand gun (Gunbody No. 102) was mounted in HMS Resolution from 1915 to 1938. It saw service in the Sea of Marmara in 1920, but was not fired in anger again until 1944, and then in another ship, the monitor Roberts. This ship was an important unit in the naval forces assembled for the invasion of Normandy. On D-Day itself, HMS Roberts bombarded Houlgate Battery, east of Sword Beach. During the succeeding weeks her guns shelled enemy positions several miles inland near Caen. On 1 November 1944 she supported the assault on Walcheren and attacked a German battery north of Westkapelle.

This gun was made by Vickers, Son & Maxim. It was stored from 1938 to 1944 and again from 1945 onwards. The breech mechanism on this gun was originally used for instructional purposes at Woolwich Arsenal. It was fitted to the barrel by Museum craftsmen with help from the Arsenal. The tampion badge - a charging knight - symbolises 'Resolution'.