A commercial diver who discovered a haul of historic cannons has pleaded guilty to fraud totalling more than £46,000.

Vincent Woolsgrove from Ramsgate reported finding five cannons during the summer of 2007 - two from the wreck of the warship London and three in international waters off the coast of Kent.

The bronze cannons recovered from London were both very rare while the three he reported finding off North Foreland were 24lb bronze cannons originally from Amsterdam.

Mr Woolsgrove was awarded ownership of the three Dutch cannons, as the Maritime and Coastguard Agency (MCA) was unable to prove the cannons were property of the Crown.

They were sold at auction to an American buyer for more than £50,000 and are now in a private collection in Florida.

"This case sets an important precedent in the fight against uncontrolled salvage by a small criminal minority who have no appreciation for England's maritime heritage" - Historic England

Information about divers stealing cultural objects of great historic value from wrecks off the coast sparked a joint operation between the MCA, Kent Police and Historic England.

A search warrant was obtained and Woolsgrove’s house was searched.

In his garden, investigators found a bronze 16 century Zeirikzee cannon in a desalinisation tank along with other wreck items including copper, lead, tin and glass ingots and ship’s bells.

Woolsgrove was interviewed and disclosed he had a further two unreported bronze armada cannons stored at his girlfriend’s house.

When he was questioned regarding the previous Dutch cannons he stated that they were recovered from North Foreland but were towed to the Thames Estuary.

During the investigation, photographs were found on his computer showing the cannons being recovered off Southend.

Extensive research was then untaken by the MCA, world authority on muzzle loading cannons Charles Trollope and Frank Fox, an American author of 16 and 17th century British naval history as well as the Dutch heritage authorities.

They proved the three Dutch cannons had been issued to Dutch vessels Groote Liefde and St Mattheus to attack the English fleet during the first Anglo-Dutch War in 1653.

The cannons were part of a battery of 36 cannons produced in Amsterdam to protect the city in the early part of the 16th century, and were assigned to Dutch ships during the first Anglo Dutch war.

“The laws on salvage are very clear and they work well when properly applied. Those tempted to circumvent those rules can expect our close attention” - Maritime and Coastguard Agency

These vessels were captured by the English and the cannons taken as prizes.

The cannons were later placed on board London until it blew up in 1665 with the loss of more than 200 souls of Southend when a powder magazine exploded.

This evidence disproved Mr Woolsgrove’s claim he had found the cannons outside territorial waters and they were property of the Crown.

If he had reported them correctly he would have been entitled to a substantial salvage award.

Woolsgrove will be sentenced on September 4 at Southampton Crown Court.

David Knight and Edward Huzzey, who dived with Woolsgrove were convicted of several offences in relation to unreported wreck material including further bronze cannons.

Sir Alan Massey, chief executive of the Maritime and Coastguard Agency said: “This is an important case and should serve as a deterrent to others.

“The laws on salvage are very clear and they work well when properly applied.

“Those tempted to circumvent those rules can expect our close attention.”

Historic England provided expert advice in relation to uncontrolled salvage on submerged archaeological remains and on the handling of the seized artefacts.

Mark Harrison, Historic England's national policing and crime advisor, said: "This case sets an important precedent in the fight against uncontrolled salvage by a small criminal minority who have no appreciation for England's maritime heritage.

"Woolsgrove used sophisticated techniques and equipment to remove these valuable artefacts from the seabed."

The London was a second-rate warship built in Chatham dockyard in 1654 and became part of Charles II’s restoration navy.