Two men who stripped an estimated £150,000-worth of metal from UK shipwrecks, including the protected WW1 war grave HMS Hermes in the English Channel, have been jailed for fraud.

Experienced diver Nigel Ingram, 57, of Teynham in Kent, UK, and boat-owner John Blight, 58, of Winchelsea in East Sussex, UK, had denied the charges but were convicted on 22 June following a trial at Canterbury Crown Court.

The jury was told that French marine-surveillance officers had boarded Blight’s vessel De Bounty in French waters near the Hermes wreck in September 2014 while Ingram was carrying out a dive.

The Hermes battle-cruiser had been converted into an aircraft ferry and depot ship before the outbreak of war in 1914, but was sunk by a U-boat in the Dover Strait that October, with the loss of 44 lives.

Ingram and Blight were not detained by the French authorities but lifting equipment present on the vessel led them to examine the wreck three days later. The condenser was found to have been removed.

A criminal investigation was launched and referred to Kent Police. The UK’s Maritime & Coastguard Agency warned Ingram about failure to declare salvage to the Receiver of Wreck, after which he reported three port-holes from fishing vessels and chinaware.

But in early 2015 officers searched his home and found some 100 items of wreck of unknown origin, including ships’ bells, a torpedo-hatch and large quantities of metal ingots.

Records showed that Ingram had made frequent visits to the APM Metals scrapyard in Sittingbourne, Kent, between May 2012 and December 2015, depositing more than six tonnes of metal there. The visits corresponded with entries in a notebook titled “De Bounty Diver Recovery” found at his home.

Ingram had cashed a £5029 cheque from the scrap-merchant on 1 October 2014, the day after the French officers had boarded his boat. A safe containing £16,000 in cash was also found at his home.

According to the police the value of wreck collected but not reported to the Receiver of Wreck was estimated at more than £150,000.

Ingram, convicted of four counts of fraud and one of money-laundering, was sentenced to four years in prison, while Blight, found guilty of four counts of fraud, was given a 3.5-year jail-term.

“Nigel Ingram and John Blight worked together to retrieve metal from a sunken warship on the seabed in order to enrich themselves,” said Richard Link, from the Crown Prosecution Service.

“Both men knew of their legal obligations to declare wreck recovered from the seabed. Their failure to declare the metal in order to sell it on for profit not only meant that they were guilty of fraud but also resulted in irreparable damage to sites of historical importance,” he said.