Rendered obsolete with the emergence of the new dreadnoughts in late 1906, she underwent an extensive refit in 1909, after which she served with the Atlantic Fleet.

She was assigned to the Second Home Fleet in 1912 as part of the 5th Battle Squadron, and was temporarily fitted with a makeshift ramp for experiments with naval aircraft until 1913.

Returning to the United Kingdom, she was inactive until being converted to a minelayer in early 1918, which entailed the removal of her main armament.

The Formidable-class ships were powered by a pair of 3-cylinder triple-expansion engines that drove two screws, with steam provided by twenty Belleville boilers.

[3] London commissioned at Portsmouth Dockyard on 7 June 1902 for service in the Mediterranean Fleet,[4] with Captain James Goodrich in command.

Her refit complete, London commissioned at Chatham on 8 February 1910 to serve as Second Flagship, Rear Admiral, Atlantic Fleet.

[15] Upon the outbreak of the First World War in August 1914, the 5th Battle Squadron was assigned to the Channel Fleet and based at Portland.

It was briefly planned to deploy the squadron to replace the ships lost during the action of 22 September 1914 but the orders to transfer to the Medway were rescinded.

By the end of the month, only London, the battleships Queen, Prince of Wales, and Implacable, and the light cruisers Topaze and Diamond were at Portland.

[19] In March 1915, as the British and French fleets waging the Dardanelles campaign were preparing to launch a major attack on 18 March, the overall commander, Admiral Sackville Carden, requested two more battleships of the 5th Squadron, Implacable and Queen, to be transferred to his command in the expectation of losses in the coming operation.

By the time they arrived, the British had lost two battleships in the 18 March attack, prompting the Admiralty to finally disband 5th Squadron and send London and Prince of Wales to join the fleet.

[20] Before they departed, they were modified slightly for operations off the Dardanelles, including the installation of a pair of 3-pounder anti-aircraft guns on their quarterdecks and the re-installation of anti-torpedo nets.

On her arrival in the eastern Mediterranean, London joined the 2nd Squadron, commanded by Rear Admiral Cecil Thursby.

[11][21] London, along with battleships Implacable, Queen, and Prince of Wales, was transferred to the 2nd Detached Squadron, organised to reinforce the Italian Navy in the Adriatic Sea when Italy declared war on Austria-Hungary.

In October 1916, London returned to the United Kingdom, paid off at Devonport Dockyard to provide crews for antisubmarine vessels, and was laid up.

[22][12] The conversion was completed in April 1918, and on 18 May 1918 London recommissioned at Rosyth for service in the Grand Fleet's 1st Minelaying Squadron.