Le Bailly served on HMS Hood, 1932; at the Royal Naval Engineering College, 1933-37; on HMS Hood, 1937-40; on HMS Naiad, 1940-42; at RNEC, 1942-44; on HMS Duke of York, 1944-46; at the Admiralty, 1946-50; on HMS Bermuda, 1950-52; at RNEC, 1955-58; at the Admiralty: as Staff Officer to Dartmouth Review Committee, 1958; as Assistant Engineer-in-Chief, 1958-60; as Naval Assistant to Controller of the Navy, 1960-63; as IDC, 1963; as Deputy Director of Marine Engineering, 1963-67; as Naval Attaché, Washington, DC, and Commander, British Navy Staff, 1967-69; at the Ministry of Defence, 1970-72; he was appointed Vice-Admiral in 1970 and retired in 1972. He was subsequently appointed Director-General of Intelligence, Ministry of Defence, 1972-75. He is the author of, "The Man Around the Engine", 1990; "From Fisher to the Falklands", 1991; "Old Loves Return", 1993.