 Oke's half-brother John Langdon Oke (1776–1812) joined the Royal Navy in 1790.He served aboard during the mutiny at Spithead (16 April to 15 May 1797) and as a master's mate on , under the command of Captain Charles John Moore Mansfield, apprehending French privateers along the Irish coast and blockading Swedish and Portuguese merchant ships.In 1803, he was aboard chasing the French corvette "Bayonnaise" in Finisterre Bay, Spain, and was on when it captured the "Frisken" in the Mediterranean on 7 May 1805.