The barrel of the cannon had been plugged with a tampion of wood and sealed with candle wax by sailors more than 400 years ago.

The stale air of another age whistled out with a hiss when the seal was broken finally last week. Archaeologists gathered around the weapon could smell the gunpowder and hydrogen sulphide as it escaped.

The cannon is one of a set that comprises the first archaeological evidence of a revolution in weaponry that took place during the reign of Elizabeth I – a revolution upon which an empire would be built.

The archaeologists have spent the past month raising the cannon from the seabed off the Channel Islands and will use it to determine the power that this revolution bestowed upon the English naval forces.

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A replica is to be cast in iron, transported to a quarry in the Midlands and fired at a replica of the side of an Elizabethan ship.

Ballistics experts will measure its range. The archaeologists will examine its handling and recoil, and the damage that it could inflict.

The cannon is one of three raised from a wreck half a mile off the tip of Alderney. The location of the wreck matched the final position of a ship that, according to the records, was “cast away about Alderney” on October 27, 1592. The ship had been carrying dispatches from Lord Burghley, the Queen’s principal adviser, to Sir John Norreys, her most experienced soldier, who was in Brittany commanding an army against the Catholic League and the forces of Philip II.

It was a moment of crisis in English history. Four years after the failure of the Armada, the King of Spain wanted to secure a stretch of coastline and a deep-water port from which he could launch an invasion. Sir John and a small army had been sent to fight the Spanish-backed Catholic League beside the French king, Henry IV.

Mensun Bound, the excavation director for the Alderney wreck, said: “She was probably a small ship, agile on the wind.” She was also armed to the teeth with the latest in weaponry.

Mr Bound, a senior research fellow at St Peter’s College, Oxford, has also worked on the Mary Rose, which was armed with a random assortment of crude weaponry when it sank in 1545.

The significance of the Alderney ship became clear to him as he examined the shot excavated from the wreck. “Every single piece of shot was the same, with a variation of less than 1.5mm (0.06 inches).” This suggested that more than one set of Elizabethan cannon were on board.

Marine archaeologists could see six sediment-clad cannon protruding from the sand, part of a set of matching high-performance cast-iron guns.

Their basic design would be the pattern of English cannon until the time of Nelson.

Professor David Loades, a Tudor historian, told The Times: “We knew that a revolution in weaponry had taken place in the years before 1592.

“There was quite a lot of documentary evidence but there was no archaeological evidence.”

The first cannon to be raised from the wreck was also sealed with a tampion and wax.

Mr Mensun said: “When we opened it there was a spontaneous combustion of gun powder. It started to smoke.” The historians ran in all directions, fearing a discharge.

Another two cannon were raised last month and brought up the Thames to the Tower of London last week, where investigations continue.

www.alderneywreck.com

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