Cabot, having forsaken Italy for Bristol, had in that spring and summer sailed westward over the Atlantic in a small ship, the Matthew, and eventually sighted land. Returning to Bristol with the story of his discovery he had been greeted as a hero, mobbed in the streets and lionised as the "Great Admiral". The parsimonious Henry VII was even moved to reward him with a special grant of £10.
Christopher Columbus's discovery of land to the west was by then five years old so this English voyage was not exactly a first, but the Duke of Milan's correspondent was struck by one aspect of Cabot's story.
It seemed that around the New-Found-Land in the far west, "the sea is full of fish which are taken not only with the net, but with a basket in which a stone is put so that the basket may plunge into water. And the Englishmen, his [Cabot's] partners, say that they can bring so many fish that the kingdom will have no more business with Iceland, and that from this country there will be a very great trade in the fish they call stock fish".
Stock fish was cod, but it turned out that these waters contained not only cod but herring, lobster, whales and - as the recent spat between Canada and Spain over the seizure of the Estai has highlighted - turbot. The Newfoundland Grand Banks are, or at least were, the richest fishery anywhere in the world.
Cabot was not the first to venture into these waters - the Viking, Lief Ericsson, had been there in the 10th century and the occasional European boat had passed that way since the 1450s. It was Cabot, however, who put the fishing grounds on the map.
Their bounty became a matter of legend, the ultimate fisherman's tale. The cod were so plentiful, it was said, that a dog could run into the water and catch one in its teeth; bears lived off them. A writer in 1620 said the fish were "so thick by the shore ... I have killed of them with a pike".
Cabot's discovery was an event of strategic and economic significance akin to striking North Sea oil. As a Newfoundland historian wrote: "Codfish was gold in these old days." Meat in Tudor England was expensive and difficult to preserve, and fish - fresh, salted or dried - was a staple food for ordinary folk. A plentiful new supply was clearly valuable.
A pattern was soon set. Boats sailed from West Country ports in the spring, often picking up cheap Irish labourers on the way. Drying and salting plants were established on the Newfoundland shore and worked by the Irish while the boats headed for the banks to fish. In the early days this was often done by men with lines and hooks, leaning from special gantries lowered down the sides of the boats.
So abundant was the harvest that a special "carrying-fleet" was needed to ply the Atlantic in the summer, bringing the fish back for sale in Europe. The season ended in the autumn, and everyone returned home, leaving the shore settlements deserted.
But it was not just the English who took advantage of these fishing grounds. Over the next century French, Portuguese and Spanish boats also went about their business on the Grand Banks and in ever greater numbers. By 1578 one captain reported no fewer than 400 ships at work there, of which only a quarter were English. Moreover the Spanish, who were mainly Basques, had the biggest boats, of 300-400 tons.
Given the diplomatic tensions between Catholic Spain and Protestant England at that time, it was no surprise that fishing rights were to prove a matter of contention. In 1583 English ships were impounded in Spanish ports, and Queen Elizabeth's government chose the Grand Banks as the place to retaliate. A small fleet that was already on its way to the New World under the command of Sir Bernard (not Sir Francis) Drake was diverted to the fishing grounds. There they rounded up what Spanish and Portuguese vessels they could find and hauled them back to England. Six hundred sailors were captured, of whom many died of fever, and 2,500 tons of fish were confiscated. Spain was outraged, and the row played its part in the build- up to the sending of the Spanish Armada five years later.
Since that time the waters around Newfoundland - which used to be known as England's first, or premier, colony - have been the scene of more or less continuous fishing disputes. After the Spanish, it was the French. The Treaty of Utrecht of 1713 gave France vaguely defined rights in the area, prompting haggling and feuding which continued until 1904 (when the rights were traded against British border concessions in Africa). Then there was a bitter row between Canada and the US, and now, after four centuries and with the great fishery depleted, it is the Spanish again.