Navy List regulations, 2005
Current rules on merchant ships entitled to fly the Blue Ensign:
ROYAL NAVAL RESERVE AND OTHER VESSELS AUTHORISED TO FLY THE BLUE ENSIGN IN MERCHANT VESSELS (FOREIGN OR HOME TRADE ARTICLES) AND FISHING VESSELS.
A list of Royal Naval Reserve and other vessels authorised to fl y the Blue Ensign will no longer be published in the Navy List.
Its inclusion was intended for the information of Captains of Her Majesty’s Ships with reference to the provisions of Article 9153 of the Queen’s Regulations for the Royal Navy under which they are authorised to ascertain whether British Merchant Ships (including Fishing Vessels) flying the Blue Ensign of Her Majesty’s Fleet are legally entitled to do so.
However, the usefulness of this list serves only a limited purpose as the list of vessels that could fl y the Blue Ensign can change frequently. British merchant ships and fishing vessels are allowed to wear the plain Blue Ensign under the authority of a special Warrant, subject to certain conditions being fulfilled, and which are outlined below.
Vessels registered on the British Registry of Shipping may wear a plain Blue Ensign providing the master or skipper is in possession of a warrant issued by the Director of Naval Reserves under the authority of the Secretary of State for Defence, and the additional conditions outlined below are fulfilled. The Blue Ensign is to be struck if the officer to whom the warrant was issued relinquishes command, or if the ship or vessel passes into foreign ownership and ceases to be a British ship as defined by MSA 95.
Vessels on Parts I, II, and IV of the Register. The master must be an officer of the rank of lieutenant RN/RMR or Captain RM/RMR or above in the Royal Fleet Reserve or the maritime forces of a United Kingdom Overseas Territory or Commonwealth country of which Her Majesty is Head of State, or an officer on the Active or Retired Lists of any branch of the maritime reserve forces of these countries or territories.
Vessels on Part II of the Register. This part of the Register is reserved for fishing vessels. The skipper must comply with the same criteria as for sub-Clause 4.a. above, however the crew must contain at least four members, each of whom fulfils at least one of the following criteria: Royal Naval or Royal Marines reservists or pensioners Reservists or pensioners from a Commonwealth monarchy or United Kingdom Overseas Territory Ex-ratings or Royal Marines who have completed twenty years service in the Reserves Members of the Royal Fleet Reserve.
Action on sighting a merchant ship wearing a Blue Ensign. The Commanding Officer of one of HM ships on meeting a vessel wearing the Blue Ensign may send on board a commissioned officer to confirm that the criteria outlined above are being met in full. If it is found that the ship is wearing a Blue Ensign, without authority of a proper warrant, the ensign is to be seized, taken away and forfeited to The Sovereign and the circumstances reported to the Director Naval Reserves, acting on behalf of the Commander in Chief Naval Home Command, who maintains the list of persons authorised to hold such warrants. However, if it is found that, despite the warrant being sighted, the ship is failing to comply with the criteria in some other particular, the ensign is not to be seized but the circumstances are to be reported to the Director.
Source: The Navy List (2006) (p. 287)
Andrew Thomas, 14 November 2005
I will investigate further!