Thanks to the various PLA initiatives, London maintained its traditional position as the world's largest port.
Between 1909 and 1939 the total tonnage of shipping going through the port rose from less than 40 million tons to more than 60 million. London's share of Britain's sea-borne trade rose from 29% to 38%.
John Masefield, the Poet Laureate, visited the PLA's Cutler Street Warehouses. He marvelled at the imports stored there:
You showed me nutmegs and nutmeg husks, Ostrich feathers and elephant tusks, Hundreds of tons of costly tea, Packed in wool by the Cingalee, And a myriad of drugs which disagree. Cinnamon, myrrh, and mace you showed, Golden Paradise birds that glowed, More cigars than a man could count, And a billion cloves in an odorous mount, And a choice port wine from a bright glass fount.
You showed, for a most delightful hour, The wealth of the world and London's power.
It had dredged a channel 80 kilometres (50 miles) long, 300 metres (1000 feet) wide and nearly 10 metres (30 feet) deep at low water, to take large ships.
On the eve of the Second World War 100,000 dockers and other workers depended on the PLA. More than 30,000 were actually employed by the PLA itself.
The port declined in the period between 1965 and 1981. The East India, London, Surrey and St Katharine Dock closed in the late 1960s and early 1970s. And between 1980 and 1983 the West India, Millwall and the Royal Docks shut.
Changes in the pattern of global trade explained the closures. Many of Britain's trading partners were developing their own manufacturing industries and finding new markets for their goods.
For example, Australia, which had sent most of its wool to Britain, was sending more to Japan by the 1960s. Europe was also becoming a more important trading area. As a result continental ports like Rotterdam, making full use of new mechanized dock technology, began to overtake London.
The inner London docks went out of business because of several reasons, including competition from foreign ports, outdated equipment, inflexible management and restrictive labour practices.
However, the main reason was the increasing use of container ships, which required deep-water berths further down the Thames.
Containerization revolutionized dock work. Warehouses were no longer needed since the metal containers provided protection for their contents. All that was needed was a lot of space to stack the containers ready for collection.
There was no space available in London. Purpose-built container terminals, like those at Tilbury and Felixstowe, became the main site for this activity.
Tilbury and Felixstowe
Tilbury and Felixstowe were better able to take advantage of the growth in Britain's trade with mainland Europe. This was because of their easier access and shorter sea routes.
Tilbury's wharves and warehouses were subsequently modernised to include facilities for containers, bulk cargoes (e.g. steel and grain) and roll-on, roll-off ferry traffic.