In 1910–1911, the four-inch guns on the roof of the forward turret of Vanguard were replaced by a rangefinder. This was removed about a year later, roughly at the same time when the rooftop guns were removed from the forward turrets of the other two ships.Burt (1986), pp. 80–81. In late 1914, the remaining rooftop guns were replaced on the three sister ships by 9-foot rangefinders protected by armoured hoods.Admiralty Weekly Order No. 455 of 6 October 1914, referenced in footnotes 16 and 17,
