Locker initially held a number of administrative posts in the Navy, concluding his career as private secretary to Lord Exmouth (1757–1833; DNB) during the latter’s time as commander in the Mediterranean, 1811–1814. Southey first wrote to Locker in search of information for his History of the Peninsular War (1823–1832), but the two shared many interests and the correspondence continued. Locker was the editor of the patriotic journal, the Plain Englishman (1820–1823), to which Southey contributed poems, and played an important role in developing Greenwich Naval Hospital 1819–1844.