When John Henry Montagu Manners, the 9th Duke of Rutland, died of pneumonia on April 22, 1940, he was remembered as a soldier who fought with comrades on the Western Front.
His name and rank formed the centrepiece at the chapel at Belvoir Castle as a tribute to his virtuous war record.
But the Duke had spent his final days locked in a dank room at the castle, frantically trying to erase any record of his involvement in the Great War.
In all, 249 men from the Belvoir estate were killed fighting on the frontline in France between 1914 and 1918. The Duke was never among them.
Despite leading the Remembrance Day parade through Rutland year after year and presiding over the ceremony, his supposed military service was a sham – but not one of his own making.
His mother, Violet Manners, the 8th Duchess of Rutland, used her considerable persuasive powers and position to approach Lord Kitchener and Sir John French, the Commander in Chief of the Western Front, to keep her son from the fighting.
Eventually, she rigged a series of medical examinations and dashed any hopes John had of battling in the trenches in Ypres with his regiment – the 4th Battalion Leicestershire (the Tigers).
In the years before he died, ashamed of his sham military service, the Duke became reclusive as he obsessed over the family's meticulous records.
His aim was to erase any reference to his military past and rewrite the family's history – and he succeeded.
However, the truth did not come to light until historian Catherine Bailey began combing through the records in 2008.
"The archive was prist-ine," she said. "It went all the way back to the 12th century and included tens of-thousands of documents.
"But when I began studying them, I noticed gaps."
On April 22, 1940, the Leicester Mercury reported "with great regret that the Duke of Rutland, head of the ancient family of Manners, died at his seat".
The article paid tribute to the 53-year-old, stating: "He went to the front in February 1915, serving with the rank of Captain."
Catherine said: "The family had no idea John had altered documents and letters and rewritten history. It was only when I unearthed a small trunk containing more letters I was able piece together the clues and unravel what had happened."
Catherine first entered the Muniment Room at Belvoir Castle – where the family archives are kept – in 2008, after the Duke and Duchess of Rutland agreed to let her research the family for a book about the First World War.
"My original idea was to write about a great family during the Great War and the Duke and Duchess agreed to take part. But after just a few months, I noticed things were missing from the records," she said
Catherine found three gaps – 1894, 1909 and 1915 – in the otherwise perfect chronological archive.
"It soon became a detective story," she said.
The first gap related to the death of John's brother, Haddon.
"When John was eight his brother died, but the reason for the death was not what the family believed had happened to him."
Catherine stops there. "I don't want to give too much of the book away," she explains.
"John was banished from Belvoir Castle on the day of Haddon's funeral and spent most of his childhood years estranged from his parents.
"That event is the key to his character and shaped the rest of his life."
Haddon's death shook Violet, his mother, who made no secret of the fact he was her favourite.
But the tragic event had further implications. Were anything to happen to John, she would lose her money and privileges when her husband – the 8th Duke – died.
His title and estate would be handed over to his half-brother, leaving Violet penniless.
Catherine believes the Duchess's efforts to keep her only son from the frontline were motivated by neurosis rather than love.
"She did everything she could to prevent him from fighting on the frontline, because the most likely outcome of being on the Western Front was being killed," she said.
It was true John was a Captain in the 4th Battalion, Leicestershire Regiment before it was absorbed into the 46th North Midland Division.
He was appointed aide-de-camp to General Edward Montagu-Stuart-Wortley, a role which included instructing soldiers in Britain.
However, when he was sent to Ypres, France, in 1915, much to his frustration, he only witnessed the Great War from the safety of Goldfish Chateaux, the Army's regional headquarters.
John's exclusion from the carnage of the frontline was due to his mother's relentless interference.
Violet wrote letters to GHQ (General Headquarters) and General Wortley and even pressured her daughter into seducing a man whom she thought would be able to influence senior officers.
She finally turned to family physician Dr Donald Hood to give false evidence about John's health, claiming he had recurring dysentery.
"The more I got to know him, the more his story became a tragic one," said Catherine. "For the first year of the war he did all he could to fight with the men of the 4th Leicesters.
"But it was his mother's meddling and constant undermining that finally got him returned home.
"He spent the rest of life ashamed and his final years locked away trying to erase his past."
The Secret Rooms, published by Penguin, is out on November 1.