Important changes to the shipping industry were made during the Second World War. The level of government control was unprecedented, first affecting the Ministry of Shipping and the Ministry of Transport, and later the all-encompassing Ministry of War Transport.
As the Second World War was more widespread and intensive than the First World War, equipment was larger and heavier, and logistical support for the armed services greater. Requirement for imports to support the war economy was high, and systems for the rationing and tight control of raw materials and foodstuffs were established.
The shipping industry again suffered heavy losses, notably from attacks by enemy submarines. Construction in order to replace losses ran at a high level. Transfer of American-built liberty and victory ships and T2 tankers to the Ministry of War Transport hugely aided replacement. The home built 'empire' design of dry cargo vessels also aided replacement.
Britain's merchant fleet had grown in size by the end of the war, and conditions continued to improve in the immediate post-war years. Decolonisation meant many newly independent countries (such as India) reserved trade for their own national flagged merchant fleets. This reduced the global market from British shipping lines. Other countries also regularly subsidised their own merchant fleets, but Britain did not.
British companies attempting to replace old ships faced strict governmental exchange controls. Most requests were refused until the late 1950s, placing the British shipping industry at the mercy of the shipbuilding industry. Due to poor working conditions and other problems, the shipbuilding industry was experiencing strike action and often ships were not delivered on time or at the agreed price. Ships available to foreign competitors were frequently superior in design and quality. British shipping was also hampered by the development of 'Flags of Convenience', the process of transferring registration from a national registry to another with lower costs.
From the 1960s, the use of new containerised cargo handling made the traditional British 'tramp' obsolete, and transatlantic airlines soon ended the age of the passenger liner. Use of bulk carriers and container vessels forced a change in shipping infrastructure. The new larger vessels - no matter who owned them or where they were registered - didn't fit in the old docks in London, the Thames estuary, Liverpool, the Clyde and Bristol. New docks at Avonmouth, Felixstowe and especially Harwich were used instead. Specialist oil and bulk commodity handling facilities at Fawley, Hunterston and Finnart Ocean Terminal were developed. The old Victorian docks and their associated industries became obsolete and were eventually redeveloped for residential and consumer use.