The British Merchant Navy was historically one of the largest ship registries and source of crew in the world, with 33% of global tonnage registered in 1939.

However, since the mid 20th century, the number of shipowners, ships, officers and crew have declined dramatically as a result of globalisation and the rise of flags of convenience.

The Merchant Navy has been in existence for a significant period in English and British history, owing its growth to trade and imperial expansion.

It can be dated back to the 17th century, when an attempt was made to register all seafarers as a source of labour for the Royal Navy in times of conflict.

The lucrative trades in sugar, contraband opium to China, spices, and tea (carried by ships such as the Cutty Sark) helped to entrench this dominance in the 19th century.

In 1928 George V gave Edward, Prince of Wales the title of "Master of the Merchant Navy and Fishing Fleets";[8] which he retained after his accession to the throne in January 1936 and relinquished only at his abdication that December.

The United Kingdom alone suffered the loss of 11.7 million tons, which was 54% of the total Merchant Navy fleet at the outbreak of the Second World War.

[12] Each locomotive of the class was named after British shipping lines from the Second World War, principally those operating out of Southampton.

[14] Historically a person wishing to become a captain, or master prior to about 1969, had three choices: to attend one of the three elite naval schools from the age of 12, the fixed-base HMS Conway and HMS Worcester or Pangbourne Nautical College, which would automatically lead to an apprenticeship as a seagoing cadet officer; apply to one of several training programmes elsewhere; or go to sea immediately by applying directly to a merchant shipping company at about age 17.

Then there would be three years (with prior training or four years without) of seagoing experience aboard ship, in work-clothes and as mates with the deck crew, under the direction of the bo'sun cleaning bilges, chipping paint, polishing brass, cement washing freshwater tanks, and holystoning teak decks, and studying navigation and seamanship on the bridge in uniform, under the direction of an officer, before taking exams to become a second mate.

This was a characteristic of the extant of the shipping companies trade, the extent of the British Empire and the availability of crew in different ports.

Crews made up of recruits from Britain itself were commonly used on ships trading across the North Atlantic, to South America and to Australia and New Zealand.

This affords a practical education, that along with the academic time in college prepares a candidate for a separate and final oral exam.

Certificates are issued for different ranks and as such an officer will usually return to complete a subsequent series of studies until they reach the highest qualification.

The first UK deck officer certificates of competency were issued in 1845, conducted then, as now, by a final oral exam with a master mariner.

[23] This training still encompasses all of the traditional trades such as celestial navigation, ship stability, general cargo and seamanship, but now includes training in business, legislation, law, and computerisation for deck officers and marine engineering principles, workshop technology, steam propulsion, motor (diesel) propulsion, auxiliaries, mechanics, thermodynamics, engineering drawing, ship construction, marine electrics as well as practical workshop training for engineering officers.

Traditionally and still now, the ships ratings are supervised by the bosun, as overseen by a responsible deck officer, usually the chief mate.

Bermuda (historically part of British North America, but left out of the Confederation of Canada) flies the red ensign also as a territorial flag on land, as did other British North American colonies that still do so as Provinces of modern Canada, including Ontario (other British Overseas Territories that fly a nautical ensign as the territorial flag on land use the Blue Ensign which in Bermuda is only flown from civil government vessels such as ferry boats).

Canadian Philip Bent, ex-British Merchant Navy, joined the British Army at the outbreak of World War I and won the Victoria Cross.

[33] Recipients must be nominated by someone other than themselves, with at least two written letters of support and are normally required to have completed 20 years service in the Merchant Navy (although in exceptional circumstances it may be less).