Without the JC archive, Lawrence Lever would never have known his great uncle, who died in the First World War, existed.

“Nobody in my family has spoken about him for nearly 100 years,” he said.

Mr Lever, who is the Executive Chairman of the financial publishing group Citywire, was shocked to read in the 1901 census that his great grandfather Jacob Levy, who had immigrated from Poland, had six children — not five.

The mystery child was Isaac levy, then 11.When Jacob Levy died in 1927, his will named his wife and five children — not Isaac.

But Mr Lever could find no records of his death. So he turned to “a tragic set of announcements… week in week out, of children killed or wounded, or missing in action” — the JC’s personal columns during the war.

But still there was no Isaac Levy. So Mr Lever entered Jacob Levy’s name and found Jacob and Fanny Levy had announced their 29-year-old son, Sergeant Harold Levy, was killed on October 2, 1918, dying instantly when a shell burst close to him.

Isaac Levy had used an anglicised name when he enlisted, Mr Lever concluded, a “common practice” for British Jews who joined up. “Harold was definitely the missing Isaac.”

The same issue of the JC — October 10, 1918 — carried a tribute to Harold Levy from his commanding officer, who wrote he “always had the welfare of his men at heart and was greatly beloved by all. When we came to attack a strong point he was as usual full of good heart and cheerfulness,” the officer said.

“We shall always cherish the fondest memories of your son, who was a hero in every sense.”

Mr Lever said this is “the most anyone has written” about his forgotten great uncle. He said his own father — Isaac Levy’s nephew — never spoke of him and may have not even known he existed. Mr Lever speculated his uncle, the late Labour politician Harold Lever, may have been named after him.

“He wasn’t buried. His name lives on the wall of the Loos Memorial at the Dud Corner Cemetery in France,” Mr Lever said. “I can only imagine the grief of my great grandparents. Perhaps their way of handling their grief was never to talk about him again.”