Survivor of Japan's brutal PoW camps, Alistair Urquhart, has finally committed his story to paper more than 60 years on

• Inmates of a Japanese prisoner-of-war camp worked naked, but for a loincloth, in appalling conditions; many starved or died of disease. Picture: Getty

Swaying around the room with dance partner Helen Scroggie in his arms, he slips away from the past and towards the peaceful present. "When I am dancing I get lost in the dance and because I'm pretty good at it, even at 90. It is something that makes me feel safe and at ease and happy," he says. These are emotions which, as a young man, he thought he would never feel again.

For the soft, crinkled features, and quiet manner of this pensioner, whose home in Broughty Ferry is decorated with his own paintings and figurines of ballroom dancers, belies the horrors he has endured and the atrocities he has witnessed.

Mr Urquhart is one of the very last surviving members of the Scottish regiment, the Gordon Highlanders, who were captured in Singapore and endured four years of brutal captivity under the lash of the Imperial Japanese army as they toiled to build the bridge over the River Kwai.

Today, his memoir, The Forgotten Highlander: My Incredible Story of Survival During the War in the Far East, is riding high in the non-fiction bestseller charts. Steven Spielberg's production company, DreamWorks, which made Saving Private Ryan and the new ten-part television drama that began in the US on Monday, The Pacific, has already contacted his literary agent, intent on securing the film rights.

Those who have read the book will understand why, for Urquhart's war-time experiences are like the Book of Job. Whatever grim situation he found himself in, it could always get worse and it always did. Yet, through it all, he survived.

He survived being packed into the hold of Kachidoki Maru, a captured US vessel renamed by the Japanese, into which so many PoWs were crammed without food or water that some drank the blood of their fellow prisoners to keep going.

He survived the ship's torpedoing by an American sub and five days on a cork raft adrift in the South China Sea. And, when eventually picked up by a Japanese whaler, he survived his final prison, a mine near Nagasaki.

For more than 60 years he said not a single word about his ordeals. The British government had insisted all PoWs take a vow of silence, but like most veterans of the Second World War he initially did not wish to speak about what he had witnessed, such as Chinese heads impaled on spikes by the Japanese, and the prisoners force-fed gallons of water while their stomachs were lashed tight with barbed wire.

When he arrived back in his native Aberdeen after the war, his mother and family tried to comfort him but he was consumed with such anger and moods that he was frequently unable to stay in the house.

He says: "When I came home, to be honest, I was lucky. I had a wonderful mother and family but my actions were disgusting really when I think back now. I just ignored what they were trying to do. They tried to get me settled back.

" I used to go straight out in the morning and walk for miles and miles and come back late the following morning. And that carried on for weeks and months. I walked through the night. I had no idea where I went, I just could not be enclosed indoors. For one thing, we had always lived in the open and I was so ill that I could not eat the food that was put in front of me. I had so many mood swings. I became completely demoralised."

Even after marrying his sweetheart, Mary, his night terrors were so extreme that one evening he awoke soaked in sweat with his hands around his bride's throat. Afterwards he began sleeping in an armchair. "Mary never asked and I never told," he explains.

"It was only after Mary's death in 1993 that I began to think about putting something down. I wrote a brief memoir for the family but it was pretty sanitised."

Then around Christmas 2008, he was approached by a literary agent who had heard about his story, and became convinced he should write it down.

Weeks after the outbreak of war in September 1939, Urquhart was conscripted into the Gordon Highlanders and, by Christmas of that year, he was based in Singapore, surrounded by complacent colonials and officers convinced of the port's impregnability.

For almost two years he spent his time competing in local ballroom dancing competitions and teaching Chinese street girls to foxtrot.

Working in the signalroom, Urquhart was the first to hear of the surprise attack by Japanese forces in December 1941. When the lieutenant general surrendered, the men were marched off to the Selarang Camp, and passed the spiked heads of 50,000 Chinese slaughtered in the Sook Ching massacre.

From Selarang, they were herded onto a cattle train for Thailand, a journey which took five days without food and water. Those that survived embarked on a 100-mile hike into the jungle where they began work on the Thailand to Burma railway, or "Death Railway" as it became known on account of the 16,000 PoWs and 100,000 native slaves who lost their lives in its construction.

Here Urquhart toiled dressed only in a loincloth 18 hours a day for the next 700 days. When he came down with tropical ulcers, he used maggots recovered from the latrines to eat out the dead flesh. Camaraderie and friendship were not the way to survive in the camp, instead Urquhart toughened himself to the suffering of others and concentrated instead on his own survival.

He says: "I had one or two pals at the beginning and they became sick, as I did. We sort of helped each other, and they died, and you watch that happening, and it was then that I made the conscious decision that there is only one way to survive here. And that was to psych yourself up every morning and keep your eyes and ears open, and I think I proved that."

When Urquhart resisted the sexual advances of a Japanese guard he was tortured for 24 hours by Lieutenant Usuki, whom he dubbed the "Black Prince". He made Urquhart hold a heavy weight above his head, then beat him savagely each time he dropped it. The real ordeal began as he was locked into one of the tiny cages called "black holes" which were covered with corrugated iron and baked whoever was crushed inside. He survived seven days.

For months Urquhart's squad worked on the construction of the Bridge over the River Kwai and years later, when he finally saw David Lean's 1957 movie on television, he reacted badly. He recalls: "I very nearly put my foot through the television: it was an insult to us; it was a shocking exposure of what never really happened." Then he adds: "My book is what happened."

After surviving an outbreak of cholera – he was the only man to come out of the cholera ward alive –- he and 900 other PoWs were sent back to Japan onboard the Kachidoki Maru. When torpedos from the US submarine Pampanito slammed into the hull, the water pressure blew Urquhart out of the ship and into the water. As an oil tanker had also been sunk in the convoy, the water that he swam through was thick with petrol.

He says: "The sinking was the worst point. I don't think you could imagine what it is like to be in the middle of the South China Sea with not a thing on the horizon but water. You are on your own, the sun beating down, you are covered in oil, the thirst is unbearable. That was the worst, but the reason why I spend time in the book talking about my youth is to show what I learned as a boy scout helped me when I was sunk.

The thing was I knew I had to keep awake and that is very difficult in those circumstances. So I did a stock-taking of the warehouse where I used to work just to keep myself from falling asleep."

After being picked up by a Japanese whaler, he and the other prisoners were taken to Hainin Island where they were paraded through the streets naked in a downpour. The prisoners still managed a chorus of Singin' In The Rain.

He was later sent by another ship to the port of Nagasaki where he worked in the coalmines. One day he was outside when a massive plane flew overhead. He remembers looking up then, a few minutes later, being blown off his feet by a blast of hot air. The American B-29 bomber had dropped Fat Man, an atomic bomb onto the city. The war with Japan was over.

Yet for Urquhart it would never be truly over. The Japanese have never properly atoned for their war crimes, he says, and he has never, and will never, forgive them for what they did to him and his comrades.

As a businessman running a plumbers merchant, he refused to buy Japanese cars for sales reps: "Even though I thought the Japanese car might be better – no way." He adds: "I still feel that the present generation of Japanese are still being brought up in the same cult as their forefathers. Japanese children going to school, bowing to the emperor and playing with sticks like Bushido – it is all there."

However, he hopes that now that he is a bestselling author others reading his book, particularly the younger generation, will take away one simple message: "To forget that big word called 'can't'. 'I can't do this, I can't do that.' I hear it so often and it makes me squirm because they never even try." Then he adds with frustration: "They wouldn't have lasted five minutes in a Japanese prison camp."

The Forgotten Highlander by Alistair Urquhart is published by Little, Brown priced 18.99.