A diver has been jailed for two years after committing fraud totalling more than £46,000 by failing to say historic cannons were found off Southend’s coast.

Essex and Kent Police, Historic England, the UK Maritime and Coastguard Agency (MCA) were all involved in a two-year investigation into Vincent Woolsgrove.

In 2007, the 49-year-old legitimately reported two cannons he found on the wreck of the warship HMS London but falsely claimed that three other Dutch cannons were found in international waters off the Kent coast.

They had in fact come from the same ship.

Because the MCA could not determine the original ship the cannons came from, Woolsgrove was allowed to keep them.

He sold them to an American buyer for £46,000 in an auction in 2010, who still has the cannons in his Florida garden and does not want to return them to England.

Acting on information, Essex Police carried out a search at both the homes of Woolgrove and his girlfriend and discovered an “Aladdin’s cave” of wreck items.

They found a 16th century Zierikzee cannon in a desalinization tank as well as another two unreported cannons When questioned about the three previous Dutch cannons, Woolsgrove still said they were recovered from North Foreland, but were towed to London.

However photographs on his computer showed the cannons being recovered off Southend.

Leading historians were then able to establish the cannons he sold were used during the first Anglo-Dutch war in 1653, given as prizes and placed on board HMS London.

The ship was blown up accidentally off Southend in 1665, killing 300 people on board.

This meant Woolsgrove, of Ramsgate, Kent, had made a fraudulent declaration about where he had found the cannons and they belonged to the Crown.

Ian Lawrie QC, prosecuting, said the cannons had been lost forever.

He said: "They are cannons of great beauty, power and rarity. Considering their rarity value, that is a considerable shame."

Sentencing, Judge Peter Ralls QC said: "The cannons are extremely rare and they are indeed unique. Other cannons were melted down or reformed, they just do not exist.

"It's great credit to the MCA that they have been able to piece together historical records from this country and the Dutch navy in Holland."

Woolsgrove was also ordered to pay £35,000 in costs and will undergo a proceeds of crime act application to recover the money he gained from the cannons sale.

Alison Kentuck, MCA Receiver of Wreck, said Woolsgrove would have been entitled to a substantial award if he had told the truth.

She said: "It is not a case of 'finders keepers', the rightful owner is always entitled to have their property back and this case shows that even where wreck artefacts are nearly 400 years old, there is still likely to be a legal owner.

"Had these artefacts been correctly reported, the finder would have been entitled to a substantial salvage award and important information could have been added to the historical record. Instead, he is facing a custodial sentence."