Section 98(2) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(2)Guards and bands shall be required at any hour between "Colours" and sunset (or 1800) on week days and 1200 on Sundays, unless otherwise ordered, when proceeding into or out of harbour, or when passing or being passed by a ship or boat flying a President's flag or Royal Standard or flag of a Distinguished personage, or by a foreign warship.
