London was originally launched as a 90-gun ship, as was standard for second rates at the time, but was later increased to 98 guns when she had eight 12-pounders installed on her quarterdeck.
Next, London participated in an abortive invasion of Ferrol. On 29 August 1800, in Vigo Bay, Admiral Sir Samuel Hood assembled a cutting-out party from the vessels under his command consisting of two boats each from Amethyst, Stag, Amelia, Brilliant and Cynthia, four boats from Courageaux, as well as the boats from Renown, London and Impetueux. The party went in and after a 15-minute fight captured the French privateer Guêpe, of Bordeaux and towed her out. She was of 300 tons burthen and had a flush deck. Pierced for 20 guns, she carried eighteen 9-pounders, and she and her crew of 161 men were under the command of Citizen Dupan. In the attack she lost 25 men killed, including Dupan, and 40 wounded. British casualties amounted to four killed, 23 wounded and one missing.[3][Note 1] In 1847 the Admiralty awarded the Naval General Service Medal with clasp "29 Aug. Boat Service 1800" to all surviving claimants from the action.[5]