More than 140 years after their ancestors started tending the grave of a British man who died in obscurity, a Japanese family has finally learned his identity – and received an official message of thanks from the British government.

For much of that period, members of the Murai family, who live in Ishikawa prefecture on the Japan Sea coast, thought they were maintaining the last resting place of a man named Philip Ward.

In fact, the grave belongs to Bernard George Littlewood, who came to Japan to teach English in 1870, just as the country was beginning to modernise.

Littlewood taught English at a school in what is now the city of Kaga, but died of smallpox the following year, aged just 30, according to the Asahi Shimbun newspaper.

Local officials erected a tombstone for Littlewood at a Buddhist temple, but months later, when feudal domains were replaced with prefectures, no one was given responsibility for its upkeep.

The Murai family, who lived nearby, decided to clean and weed the area themselves, a routine they continued throughout the second world war. Years later, the family received a letter from the British embassy thanking them for tending what was believed to be Ward’s grave.

It was not until Susumu Koyata, a volunteer who promotes international exchange in the city, researched the grave’s history that its occupant’s true identity emerged.

Koyata attributed the confusion to the tombstone’s engraving, which was etched in Kanji characters, making it difficult to pronounce.

Earlier this month, Kumiko Murai received a second letter of thanks from the British embassy thanking her for her family’s modest tribute to a forgotten expatriate.

Murai, 81, told the Asahi she had been “speechless” when the letter arrived from the current UK ambassador to Tokyo, Timothy Hitchens, who thanked her family for their kindness and for contributing to friendly ties between Japan and Britain.

The job was not without controversy, however. Murai recalled her father-in-law saying that the family had had a “hard time” during the war due to their insistence on maintaining the grave of a citizen of Japan’s then enemy.

Her 58-year-old son, Yasushi, will carry on the family tradition, she told the paper.