Three Irish divers have led the recovery of more than 400 "new" artefacts from the seabed where the Henry VIII flagship, Mary Rose, sank in the Solent.
Some 200 of the previously undiscovered artefacts are of Tudor origin and include a pocket sundial, a "kidney" dagger, gold and silver coins, chain mail, buckles and arrow shafts.
The divers also discovered a five-metre piece of wood with frames which has been identified as the missing front stem of the ship's keel.
It represents the "final piece" in the Mary Rose jigsaw and "the most important maritime archaeology find in Europe for the last 20 years", according to the project director, Ms Alex Hildred.
The stem could have been attached to the ship's "bowcastle", a "fanciful turreted structure" which has never been found but which was of a revolutionary design and was the forerunner of modern warships.
More than 100 dives were carried out by the team last month as part of British Ministry of Defence preparations for a £200 million refurbishment of the Royal Navy docks at Portsmouth.
The project represented the first major underwater archaeological work on the ship's original seabed site since 1982, shortly after the wreck was raised.
The three divers employed on the project were Mr Gareth Little, from Moycullen, Co Galway; Mr Rob Clarke, from Drogheda, Co Louth; and Mr Peter Magowan, from Donaghadee, Co Down.
The Irish divers normally work in the offshore oil industry. The fourth member of the team was Mr Nigel Boston, of Sea Boston Ltd, husband of Ms Alex Hildred, archaeologist with the Mary Rose Trust.
"All the diving was conducted from a diving bell launched from the support vessel, Terschelling," Mr Little told The Irish Times.
The 40-metre vessel was permanently moored over the site, and the divers used "surface-supplied breathing equipment", which transfers oxygen to the bell and on to the divers by an umbilical cord.
They also used a remotely operated vehicle (ROV), nicknamed Monica after Ms Monica Lewinsky, and found two gold Tudor coins and many other Tudor artefacts using this technique.
The divers worked in average depths of 13 to 15 metres, and their helmets were equipped with powerful lights and video cameras to allow their activity to be monitored and taped by a supervisor on board the support vessel.
The Mary Rose was built between 1509 and 1511 and was the pride of the Tudor fleet, being one of the first warships which could fire a broadside.
Named after Princess Mary, King Henry VIII's younger sister, it sank a mile south of Southsea Castle off Portsmouth in the Solent on July 19th, 1545, while trying to engage the French fleet moored off the Isle of Wight.
King Henry VIII watched "in horror" as the ship disappeared, and there were unsuccessful attempts to salvage it afterwards.
The Mary Rose Trust was formed in 1979. Thousands of artefacts recovered have contributed significantly to knowledge of Tudor life at sea and Tudor ship design and construction.
The ship stands in its original cradle in a purpose-built shelter over a dry dock in Portsmouth, close to where it was built. More than four million people have visited it since it was raised.
The British Ministry of Defence is anxious to clear the whole seabed area of artefacts and debris before dredging it as part of the naval docks refurbishment.
This is aimed at preparing berths for two new aircraft carriers which will be commissioned in 2012. They are the largest ever built for the Royal Navy.