5 Duty to show British flag.U.K.
(1)Subject to subsection (2) below, a British ship, other than a fishing vessel, shall hoist the red ensign or other proper national colours—
(a)on a signal being made to the ship by one of Her Majesty’s ships (including any ship under the command of a commissioned naval officer); and
(b)on entering or leaving any foreign port; and
(c)in the case of ships of 50 or more tons gross tonnage, on entering or leaving any British port.
(2)Subsection (1)(c) above does not apply to a small ship (as defined in section 1(2)) registered under Part II.