The British Merchant Navy is the collective name given to British Civilian ships and their associated crews, including officers and ratings. Previously it had been known as the Mercantile Marine or Merchant Service, In the United Kingdom, it is simply referred to as the Merchant Navy or MN. Merchant Navy vessels fly the Red Ensign and the ships and crew are regulated by the Maritime and Coastguard Agency (MCA).
King George the 5th gave the title of "Merchant Navy" on the British merchant shipping fleets following their service in WW1.
'But for the Merchant Navy who bring us the food and munitions of war, Britain would be in a perilous state and indeed, without them, the Army, Navy and Air Force could not operate' Winston Churchill