Whilst Lambert claims that Walker was First Lieutenant (The Last Sailing Battlefleet, p159), an online biography of Walker states that Walker had been promoted to commander on 15 July 1834, and was commander (i.e. executive officer or 2nd in command) on Vanguard from 1 September 1836 until 24 November 1838 (Online biography of Admiral Sir Baldwin Wake Walker (1802-1876))