This week's stunning revelation about the discovery off the Norfolk coast of the wreck of a warship which sank with the future king James II on board has made headlines around the world. JASPER COPPING reports on the vessel's historic significance

On December 23, 1688, James II stepped onto a boat at Rochester, in Kent, and headed across the Channel and into exile in France.

A fugitive, he had been forced to abandon his kingdom to his rivals - the Dutch prince William of Orange and his wife, James’ own daughter, Mary - as his support in the country evaporated.

He never returned to Britain. William and Mary took the crown. And the Glorious Revolution was confirmed.

Historians nowadays debate the exact significance of the Glorious Revolution - many dislike the use of the ‘glorious’ adjective, and earlier claims that it was a ‘bloodless’ affair are now rejected. (It certainly wasn’t in Ireland.)

But it is still accepted as a turning point in British history, like Henry VIII’s break with Rome, 150 years earlier, and the Norman Conquest of 1066.

The Glorious Revolution created a new type of state and contributed greatly to the modern world, with Britain set on its trajectory to become the world’s foremost power at the head of a vast empire.

So James II’s hurried departure from these shores, two days before Christmas Day 1688, was an important moment.

But it was not the only sea voyage he undertook which changed the course of his country’s history.

The other came six years earlier, when he boarded the Royal Navy frigate, the Gloucester, around 35 miles along the coast from Rochester at Margate.

The ship – along with a flotilla of accompanying vessels – headed up the North Sea, bound for Leith, near Edinburgh.

James – who was then the Duke of York and heir to his brother, Charles II – was, with an entourage of important figures, on his way to conduct royal business at the Scottish parliament before bringing his heavily pregnant wife back to London in time, it was hoped, for the birth of a legitimate male heir.

But as the fleet passed the Norfolk coast in the early hours of May 6, 1682, disaster struck.

At around 5.30am, the Gloucester ran aground on the Leman and Ower sandbank, located around 30 miles from Great Yarmouth and part of the network of shifting sands that have claimed the lives of so many seafarers over the centuries.

Within an hour, the ship had sunk, with the loss of up to 250 souls.

Several were saved, however, including the ship’s most important passenger, the Duke of York.

He was able to flee the stricken Gloucester in one of its small boats and be taken to the safety of an accompanying yacht, the Mary.

It was a close shave, though.

As the diarist Samuel Pepys – who witnessed the tragedy from another vessel, the Royal Yacht Katherine – later pointed out: what if the ship had run aground a few hours earlier, in darkness, or with the rest of the fleet at a greater distance, as they had been.

What, indeed?

What if the heir to the throne had drowned in those Norfolk waters?

For a start, there would have been no 1688 revolution.

Historians believe that Charles II’s illegitimate son, James Scott - the Duke of Monmouth - might well have inherited the throne on his father’s death in 1685.

Or perhaps in 1685 another civil war might have broken out, between those who supported Monmouth’s claim and those who backed James’ legitimate Protestant daughter Mary and her husband William of Orange.

Such counterfactual theories will entertain historians for centuries more.

These ‘what if...?’ moments in history are fascinating and great fun, but ultimately pointless. What is done, is done.

Yet the significance of the Gloucester’s foundering on that Norfolk sandbank is that it not only provides a tantalising ‘what if’ moment, but it also shaped what actually did happen.

The Catholic James was not a popular figure among his countrymen, even before he took the throne – hence his overthrow in 1688.

And his reported behaviour on that fateful voyage is one of the factors in his unpopularity.

James - who had served as the Lord High Admiral of the United Kingdom - had quarrelled with the Gloucester’s pilot James Ayres the evening before the wreck over the course to follow to avoid the treacherous Norfolk sandbanks.

The duke clearly influenced the choice of route but later accepted no responsibility when disaster struck.

He placed all the blame on the pilot, wishing him to be hanged immediately (though he was in fact court martialled and imprisoned).

James also delayed abandoning the sinking ship until the very last minute, which needlessly cost the lives of many who, because of protocol, could not abandon the ship before royalty.

The reputational damage he suffered as a result of the shipwreck was hugely important, say historians, because some of the powerful eyewitnesses to his behaviour clearly started to feel he was unfit to be king and later played a role in ousting him in 1688.

Of course, some of the vilification might have been flavoured by the wider dislike of James and by Protestant propaganda – his detractors also claimed that he saved his dogs and Catholic priests at the expense of the lives of his courtiers and the ship’s crew.

But if so, it was effective.

There is a straight line to be drawn, therefore, from this ill-fated North Sea voyage to James’s later ill-fated voyage to France - and to what happened in its wake.

It is this that makes the discovery of the Gloucester by Norfolk brothers Lincoln and Julian Barnwell, with their friend James Little, just so thrilling.

Comparisons have been made with the Mary Rose, the Tudor warship which went down in the Solent in 1545, before being discovered in 1971 and raised in 1982, in one of the most complex and expensive maritime salvage projects ever undertaken.

She is now on display at a multi-million pound museum in Portsmouth built specifically to house her.

Yet, in some respects, the comparison with the Gloucester is misleading.

There are not currently any proposals to raise the Duke of York’s ship.

It is not even clear the extent to which the Gloucester still exists as a cohesive structure - or is just a collection of scattered timbers on the seabed.

But what is clearer is the foundering of the Gloucester was more consequential than that of its Tudor counterpart.

The Mary Rose was a hugely historically-important vessel, remarkably well-preserved, which has provided unparalleled insights into the Tudor period.

But her sinking held less significance for the history of the realm. She foundered in a battle with the French, who were attempting to invade the Isle of Wight – but her loss did not dramatically affect the outcome.

It did not change history, in the way that the loss of the Gloucester – and James’s close shave – did.

The challenge for the region, then, is how to highlight and celebrate its proximity to this remarkable turning point in British history, without – we must assume – dredging the Gloucester’s remains from the seabed and bringing them ashore for all to see.

In the incredible Barnwell brothers, and Lord Dannatt – who is heading a committee exploring ways to promote and protect the wreck – we have a decent team to meet that challenge.