The tomb of the Unknown Warrior is the first monument that visitors to Westminster Abbey encounter, just inside the great west door. As they pause to read the inscription on the massive marble slab, many wonder about the man buried there 94 years ago and whether he was truly unknown.

The army chaplain who had the task of finding the body, exhuming it with five others and bringing them to a military base in France, where one was chosen for a state funeral, took the secret to his grave. David and Tim Kendall, son and grandson of the Rev George Kendall, say that although journalists pursued him until his death in 1961, even his family never learned the truth.

In his autobiography, only discovered among his papers after his death and still unpublished, the chaplain wrote: “It has been stated that this is the greatest mystery of the first world war. I have been interviewed from time to time by the correspondents of nearly all our great national newspapers, asking me if I knew who he was, could I say where he was actually found, who was responsible for the idea? All I can say was that he was chosen from the countless unnamed dead in France and Flanders, that the nation might honour him, and this without distinction of rank, birth or service.

“Of course one might ask from what cemetery the bodies were selected! That I cannot answer, and the knowledge I have will die with me … The location can never be revealed, but again I stress this great fact – the soldier lying in Westminster Abbey is British and unknown. He may have come from some little village or some city in this land, and he may be the son of a working man or of a rich man, ‘Unknown to man, but known to God’.”

David Kendall recalls that around this time of year, all through his childhood, there would come a knock at the door: a journalist inspired to track down his father and find out who the dead hero really was.

He is in awe of their ingenuity in finding a man whose job meant he moved house constantly – but he could have told them his father would never speak. Every year they went to the abbey where Kendall stood for a moment with bowed head: he told his son nothing of his intimate connection with the tomb.

Born in 1881, George Kendall first became a steel worker at Thorncliffe in Yorkshire and then trained as a Primitive Methodist minister. In Windsor – where he befriended Queen Mary, who invited him to tea after he was spotted outside the castle preaching on the steps of Queen Victoria’s statue – when war broke out he volunteered to go to France as chaplain with the local regiment. He survived malaria in the Dardanelles and being gassed at the Somme, reported back to the Queen about meeting the Duke of Windsor sleeping on the floor of a billet in France, and eventually became a senior chaplain with the rank of major.

George Kendall, pictured, wrote: “The soldier lying in Westminster Abbey is British and Unknown … ‘Unknown to man, but known to God’”

After 1918 he took on the grim task of exhuming all the bodies buried where they fell in Belgium, from fields, ditches, and the ruins of buildings, and moving them to the new war grave cemeteries. The appalling work led to his taking up pipe smoking, to help counteract the smell as they dug up rotting bodies and picked through scraps of uniform for clues. He was, therefore, uniquely qualified when charged with finding, exhuming, and bringing to St Pol near Arras the bodies from whom the Unknown Warrior was chosen and transferred to Dover on HMS Verdun.

On 11 November 1920, the coffin was drawn on a gun carriage through the crowded streets of London, with a guard of honour made up of winners of the Victoria Cross. As the cavalcade moved along Whitehall, two great union flags fell away at the press of a button by King George, unveiling the Cenotaph. In Westminster Abbey sat 100 women who had lost their husbands and all their sons in the war, watching as the coffin was buried under 100 sandbags of soil brought from the battlefields.

Myths and conspiracy theories have arisen about the Unknown Warrior. There are contradictory sources even on Westminster Abbey’s website. Some claimed the government knew exactly who the warrior was. Kendall contradicts this, and the romantic stories of the selection being made by a blindfolded officer in a darkened chapel.

“In all six bodies were finally taken to the headquarters at St Pol, near Arras. Those who awaited the bodies at St Pol did not even know from where they had come,” he wrote. “The six coffins were placed in a hut, and each covered with a Union Jack. All night they rested on trestles, with nothing to distinguish one from the other. The door of the hut was locked, and sentries were posted outside. In the morning a general entered the hut. He placed his hand on one of the flag-shrouded coffins, and the body therein became ‘The Unknown Warrior’.”

Kendall stayed in France and went back to work. “He had a job to do, and he would have regarded part of that job as never to speak of what he knew,” his grandson Tim, head of the charity founded in his memory, said.

He sent back vivid little sketches of his wartime experiences, bracingly cheerful and encouraging to those left behind, published in church magazines under the byline “Padre”. He also contributed to accounts of the state of postwar Germany in the Guardian. He kept his darker reminiscences – including the gangs of deserters still on the run after the war, living on their wits in abandoned ruins of Belgian villages, who fired on him at point blank range but missed – for the memoir. His family hopes the book will soon be published. Meanwhile his great granddaughter Jasmine often has a chapter as a bedtime story. “He was really good,” she said, “I’m proud of him.”