The remains of one of Ireland's most famous inventors, credited with inventing the steerable torpedo, the monorail and even the helicopter, have been found in an unmarked grave in London.

Louis Brennan, who has been described as the most famous inventor of his time, sold his torpedo design to the British navy for the equivalent of £10m in 1880 but died in near-poverty.

Historians in his home town of Castlebar, Co Mayo, say he was the first man to get a helicopter off the ground and was also the inventor of the monorail.

"He invented the dirigible torpedo and sold it to the British navy in 1880 for the sum of £110,000 which is the equivalent of £10m today," local councillor and history expert Frank Durcan told the Sunday Tribune.

"He was known as the man from Castlebar. He was the first to get a helicopter off the ground. He was one of the greatest inventors of his time – he was the inventor, worldwide, of his time – but he died virtually penniless because he invested all his money in subsequent gadgets and inventions.

"We will have to investigate the possibility of putting a proper headstone on his grave."

Last week at a meeting of the town council, a subcommittee was proposed with a view to tracing any of Brennan's family and possibly moving his body from the unmarked grave.

That may cause problems, however, as other members of his immediate family are buried alongside him in his unmarked grave at St Mary's Cemetery at Harrow Road, London, a photograph of which was recently published in the Castlebar parish magazine.

An alternative to be explored is the erection of a gravestone, with members of the Mayo business community eager to assist.

"There is a huge interest in doing something. To think that one of Castlebar's most famous sons is lying in an unmarked grave," said Councillor Ger Deere.

"A lot of businesspeople in the town have come to me to say that they want to help out with this, financially and practically."