John Sutton spent much of his life making sure he never sat with his back to the door, even decades after his time as a prisoner of war in Singapore.
His granddaughter has told Forces News that this is one of her clearest memories of how the war affected him.
"He always used to have to sit with his back to a wall so he could see who was walking through," said Wing Commander Lisa Foy, Officer Comanding, Battle Space Management Operations Wing at RAF Scampton and RAF Boulmer.
"For the whole of his life, he had that fear of someone coming up behind him and doing something to him, and that has to be a take away from his time as a prisoner of war."
She shared her grandfather's story to mark the 75th anniversary of VJ Day (Victory Over Japan) on 15 August.
Mr Sutton was one of 9,712 prisoners the Japanese kept at Changi prisoner of war camp, many of them seriously ill and starving to death.
He had joined up to fight in the late 1930s at the age of 28 and was sent to Singapore. He was there when the country fell in February 1942.
He was taken as a prisoner of war and remained there until Singapore was liberated three years later. By then, more than 12,000 prisoners of war had died in Japanese captivity.
Wing Cdr Foy said her grandfather weighed just five-and-a-half stone when he returned from Singapore.
He had spent years in the camp, sharing just a few ounces of rice with his comrades and having to forage for anything else.
He was so underweight that, when he married his sweetheart Marjorie, his suit had to be padded.
Wing Cdr Foy said: "For a lot of his life he had constant sort of digestion and stomach problems from having had such a small stomach for such a long time."
Despite this trauma, Mr Sutton was always careful to present a cheery view of his experiences for much of his life.
Wing Cdr Foy said she had found a news article from April 1946 written by her grandfather, but it was not about the hardships and horrors of his time as a prisoner of war.
"It talks about the work that the Australians and the British did to keep themselves going, the village pub that was created, the games they played, the entertainment, the black market that went on in terms of how they sold and gathered things and also the radios they made," she said.
"They managed to gather parts together and make contraband radios and what it actually says in here is the sets which brought news of our release were in two parts - half in a broom and the other half in the leg of a bed."
It wasn’t until much later in life that Mr Sutton's family decided to record his stories.
Among them is his recollection of the hospital at the Changi camp:
"The only equipment that was brought into Changi was what we had when we first surrendered," it read.
"There was little or no morphine, medicine bandages or instruments.
"At the end doctors used pen knives, kitchen knives and spoons, bandages were used over and over again.
"There were no mosquito nets and about 60 men to a hut. Men fought not to go into hospital as it was virtually one-way traffic and the chances of coming out were less than 10 percent."
Mr Sutton lived to the age of 93, devoting his time to his family and beloved wife Marjorie.
His story - along with the stories of many of his comrades - are being shared to mark the 75th anniversary of Victory Over Japan.