 In November 1901, Kerr—by then a lieutenant—was lent to the Royal Naval College, Greenwich for the compass course.In May the following year he was appointed lieutenant in charge of navigation at HMS "Hermione", serving at the Mediterranean station.After serving in the First World War, he was appointed Captain of the Dockyard and King's Harbour Master at Rosyth in 1921 and Rear Admiral of the 1st Battle Squadron of the Mediterranean Fleet in 1928.