For the best part of a century, the British Raj sent Indian dissidents and mutineers to a remote island penal colony in an 'experiment' that involved torture, medical tests, forced labour and, for many, death. Cathy Scott-Clark and Adrian Levy have unearthed official records detailing the scandal, and heard first-hand accounts from those who survived

They came for him on the fifth day of the hunger strike, with bamboo truncheons drawn. He remembered the bell in the Central Tower ringing, so it must have been 11am when they ripped back the bolts. Rough hands grabbed his forearms and thighs, one warder riding on his bucking chest. The familiar voice of Dr Edge boomed along Levels One and Two: "Teach the terrorists a lesson."

"I was lying on the cold stone floor dreaming that I could smell masala tea wafting through the wing when five of them came and knocked the wind out of me. What chance did I stand against the gorah daktar - the horse doctor?"

Living in an apartment with no bell, in a house with no number, down a lane in Calcutta that had no name, 95-year-old Dhirendra Chowdhury hadn't wanted to be found. We had to scour Calcutta to reach him. His case file was concealed among tens of thousands of logs and reports, all long forgotten, in a New Delhi vault. It was the start of a paper trail assiduously covered over by the British authorities.

Chowdhury is one of the last survivors of a British penal experiment inflicted upon more than 80,000 political prisoners. He joined the Indian freedom struggle against the Raj at 19, like many others recruited into Anushilan Samiti, a covert Bengali organisation. On October 2, 1931, he had taken part in a robbery to raise funds for bombs and guns, and the CID had intercepted his getaway car. At the age of 24, he received an unusual sentence.

Prisoner 147 was shipped to the British version of Devil's Island. Like tens of thousands of political prisoners before him, Dhirendra was manacled in the hold of a liner and carried to a remote archipelago in the middle of the Bay of Bengal.Over the past three-quarters of a century, hundreds had tried to escape from the Andaman Islands. Those who remained were routinely tortured and experimented upon by British army doctors who administered the colony, in which thousands died.

"We are forgotten victims," says Dhirendra. "Back then, all we wanted was food, and you gave us gruel that was riddled with white threads of worms. We demanded an end to work gangs, and we ended up chained like bullocks to oil mills, grinding mustard seed, around and around. We wanted medical aid for our fevers, and your doctors signed papers stating we were fit enough to flog. That's why 28 of us went on hunger strike."

Among the records of the Government of India's Home Department, we found the Empire's response in its Orders to Provincial Governors and Chief Commissioners. "Very Secret: Regarding security prisoners who hunger strike, every effort should be made to prevent the incidents from being reported, no concessions to be given to the prisoners who must be kept alive. Manual methods of restraint are best, then mechanical when the patient resists."

Now, 68 years later, spread-eagled on his bed, Dhirendra re-enacts the scene. "They rammed a tube down my nose and I tried to catch it with my tongue when it passed down my throat. Several times I succeeded, clenching the end between my teeth, but they just kept pushing harder, and eventually I felt the cool gush of liquid." An Indian Medical Committee report confirms his story. "Recommendation, 24/1629/1: A rubber catheter should be inserted through the nostril and into the gullet and so to the stomach. A solution of milk, eggs and sugar should be poured via a funnel. In certain cases rectal feeding should be tried."

"Then the screaming began," Dhirendra whispers. "We were all being force-fed simultaneously, but there was something terrible happening in the cell next door, where Mahavir Singh had been locked. The doctors at the Cellular Jail hated him." According to his case file, Prisoner 68 - Singh - was transported for driving a getaway car, his part in the killing of Lahore assistant police superintendent Saunders in December 1929. The penal colony's hospital log contains some clues as to what Dhirendra had heard.

"11am: Mahavir Singh resisted violently," Dr Edge, the British senior medical officer, had scribbled on the last page of his case notes. Two hours later, he wrote, "1pm: Patient showing signs of evident shock." By now, his handwriting was noticeably frenzied. (A government dispatch circulated to medical officers earlier that month might explain why Dr Edge had cause for concern: "In the absence of circumstances creating a right to administer food forcibly, the authorities in charge of hunger strike are liable criminally and civilly for assault.")

Dhirendra eases himself off the bed. "It took a while for the whisper to reach the Yard Five Wing. By then it was 8pm." The bell rang again. Every prisoner shuffled to his locked gate. "The feeding tube had gone into Mahavir Singh's lungs. They were filled with milk. Doctors were now fighting to revive him. So we shouted 'Inquilab Zindabad' - long live the revolution. 'Inquilab Zindabad'. Twenty-one warders ran out of the Central Tower. 'Inquilab Zindabad'. Truncheons were drawn, a gun was cocked."

"Midnight," Dr Edge noted in the penal colony's hospital log. "Mahavir Singh - dead."

Dhirendra turns his back on us. "Drowned in milk," he sighs. "Twenty-six more men on Levels One and Two now joined the strike, and nine days later more news came, tapped out on the bars in our special code with our manacles and fetters. Prisoner 89, Mohan Kishore, had also been killed. Drowned in milk. The British doctors didn't know what they were doing and yet they kept on going. Two days on, and another ra-tat-tat-tat. Mohit Mitra, Prisoner 93, was gone - the same way. How did the doctors manage to make the same mistake three times? We heard the bodies were weighed down with stones and sunk in the black water. Inquilab Zindabad? I cried and cried.

"No more talk," he says. "Ask my comrades if you want more." He pulls a faded sheet of paper out of his pocket and thrusts it into our hands. On it are the names of 27 more survivors scattered across West Bengal, Uttar Pradesh and New Delhi.

"Transportation beyond the sea is to the Hindoos... a separation forever from every tie and relation and possession which men hold to in life," Sir Robert Napier wrote in his journal, commenting on a new project unveiled in London. It was 1856, and the British medical establishment had been asked to devise a new plan for the exile of the Empire's enemies.

Army doctors were very much outriders for the Empire, accompanying regular soldiers into far-flung corners of the world, responsible for the welfare of their fellow officers as well as collecting scientific data: botanical, minerological and physiological. They often came to be in charge of operations in the remotest of areas, where practicalities such as survival were the priority.

The British military doctors had admired the penal settlement unveiled by the French six years earlier on a rocky islet off Guyana. But their Devil's Island would be far more ambitious. The doctors consulted Hindu texts and decided to create a psychological gulag based around the Sanskrit term kalapani. It literally meant "black water", but kalapani was also a myth, an ancient Indian story that told how the faithful were parted from their souls by crossing the sea. The doctors knew that kalapani would be feared across the Empire as a godless place, a journey that would strip the transported of their caste, community and creed.

On December 11, 1857, Doctors Frederick Mouat and George Playfair reached an island chain that they knew was the ideal location. Their search for a seat of revenge against "deserters and rebels" was by now all the more pressing: British Rule was paralysed by the Indian Mutiny. Three weeks earlier, Sir Colin Campbell had relieved the Residency at Lucknow to find that only 980 Europeans had survived a five-month siege. Mouat and Playfair knew, as they surveyed the terrain, that British troops were burying 2,000 dead. No one came to these islands, the doctors noted in their logs, but the half-drowned or truly desperate. For nine months a year, the Andaman Islands were caught in the crosswinds of competing monsoons, and they remained uninhabited apart from pockets of "unearthly and ferocious tribes". A better place to exile the "gigantic evil" of rebellion could not be found.

On March 10, 1858, Dr James Pattison Walker arrived at the Andaman Islands with the first batch of 200 "grievous political offenders" sweating in his ship's hold. Transportation to Australia was outlawed in 1850, but there had been no furore when the doctor's shipment had got under way from Calcutta eight days earlier.

"The jungle is so dense, and its entanglement by gigantic creepers so complete, as to render it impassable," Dr Walker wrote. Into the jungle he dispatched men in chains with orders to build their own shelters on islands Ross, Havelock and Chatham. From Calcutta and Madras, from Karachi, Singapore and Burma, the ships disgorged yet more prisoners, their crime and punishment carved on to wooden neck tickets, "so sick and debilitated that they cannot be now employed".

So many died on the voyage over that Dr Walker asked for another 10,000 to be shipped. From "sunrise to sunset", Walker wrote in his diary, "I stood uncomplaining". At the makeshift pier, he greeted new arrivals, "impressing on them the utter hopelessness of all attempts to escape". And he frightened his charges by reading to them from Marco Polo's journals an account of the indigenous tribes, dispersed across the 200 or so islands. "Every man not of their own nation," Walker declaimed, "they can lay their hands on, they kill and eat."

Within four days, the new transportees were bolting. Prisoner 61, Narain, sentenced for "having excited sedition in the cantonment at Dinapore", was the first to set out. As he was fished from the black water, hauled up before Dr Walker and executed on the approval of the medic's superiors, another convict, Prisoner 46, Naringun Singh, "guilty of desertion at Nuddea", hanged himself. By mid-April, 288 inmates, one third of those who had survived transportation to the islands, were on the run. When, on May 13, 81 of them, "driven by the murderous attacks of the savage aborigines", limped back into Port Blair pleading for mercy and medicine, Dr Walker hanged them all in a day.

When news of the summary executions reached Calcutta, JP Grant, President in Council, dashed off a letter deploring the result: "I cannot recognise any of his [Walker's] considerations as justifying the executions." But Walker escaped official censure, and on Grant's orders every inmate capable of escaping was now locked into an iron collar, so that prisoners would never again be able to flee and "excite public attention".

The doctor was finally removed from the penal project on October 3, 1859, shortly after he had proposed branding the convicts' forearms with their crime and sentence. Conditions worsened. Within four years, 3,500 out of 8,000 transportees had been killed or had died of fever, a staggering mortality rate that prompted an investigation. When Sir Robert Napier arrived in Port Blair, he found the scene "beyond comprehension". An "air of depression and despondency" clung to the islands. Why did the prisoners have no shelter, clothes or food? Only on Ross Island, where the new superintendent, Colonel RC Tytler, had settled with his wife Harriet, was there a thriving community - a European shop, turf, flowers, shrubs and a fine sandy beach.

Eight years later, Lord Mayo, the Viceroy of India, arrived at the Andaman Islands on an inspection tour. As the sun set over Mount Harriet on February 8, 1872, and the Viceroy descended from the highest point on the island chain, he announced: "This is the loveliest place I think I ever saw. Plenty of room here to settle two million men." But his vision was instantly cut down. Major General Donald Stewart, the islands' superintendent, described the scene at a subsequent inquiry. He heard the cry of "kill, kill" and then a convict "fastened like a tiger on the Viceroy's back". Major Byrne, Lord Mayo's private secretary, reported to the same panel that his superior cried out, "They've hit me."

The Government of India concluded that the killer, Sher Ali, had no known motive. They hanged him on March 11. For Irishmen who remembered Lord Mayo's tenure as their chief secretary, Prisoner 15557 became a martyr, a member of "the warrior dead". Any hope that the Andaman regime would mellow was throttled.

By the late 1870s, the monthly dispatches from the island were reading like pathology returns. "May: 20 inches of rain. Sixteen dead from diarrhoea at Aberdeen... June: 13.4 inches of rain. Convict suffering from ulcer hanged himself at Perseverance Point... July: 17.1 inches of rain. Emaciation at Bamboo Flat so extreme... men appear like veritable skeletons. Thirty-five dead."

And tucked between the pages are government approvals for secret pharmaceutical trials: "From the Secretary to the Government of India, Simla, June 24th 1880, despatch 197, to Dr J Reid, Senior Medical Officer, Port Blair: Regarding a new drug, cinchona alkaloid, the experimental use is very desirable... and should be confined to 1,000 convicts."

Dr Reid's sample group was force-fed "three grains a day" until they started to sicken. "Convict 25276. Observed on 22 March 1881. In a weak state. Bloodless. Tongue large, pale and flabby. Diarrhoea. Dead in two days."

Cinchona was a tree imported to Asia from Peru whose bark would later be distilled to make quinine, an effective and natural anti-malarial. But the rough preparation and dosage experimented with by the prison doctors caused acute side effects: nausea and diarrhoea. It was also a depressant. In monthly reports for the period of the test, the chief commissioner, Lieutenant-Colonel T Cadell, observed "a remarkable increase in suicides". Convicts "weary of life" were literally hacking each other to pieces, hoping to secure the death penalty. But Cadell had a solution: "Flogging and a reduced diet." Everyone under the age of 22 was now required to sleep in "a sort of trellis-work cage".

Escape from kalapani was surely on all the inmates' mind, and Prisoners 12819, Mehtab, and 10817, Choitun, came the closest to succeeding. They stole away from the islands on March 26, 1872, rowing out into the Bay of Bengal on home-made rafts across a 750-mile stretch of turbulent water, dodging schools of bounty hunters who fought over 250-rupee rewards (then £25). Picked up by a British vessel, they persuaded the crew that they were shipwrecked fishermen and eventually pitched up, free, at the Strangers Home for Asiatics in London. The two were fed, clothed and given a bed. But while they slept, Colonel Hughes, the home's proprietor, took photographs that were circulated around the Empire. One morning, Mehtab and Choitun awoke to find themselves shackled and frog-marched aboard the Mofassilite. They were bound for India.

A tougher regime was needed, the British government concluded, than the one that had to date processed 49,592 prisoners. At a Society of Arts lecture at London's Imperial Institute, on February 24, 1899, Richard Carnac Temple, now chief commissioner of the Andamans, unveiled a half-million rupee vision to crush once and for all the mutinous spirit. Prisoners would no longer live in barracks scattered across the malarial islands. Instead, a 698-cell panoptican was now rising out of the mangrove swamps on a promontory called Atlanta Point, overlooking the main town of Port Blair. From its Central Tower radiated seven 150-yard wings that rose to three levels, each level fitted with 52 cells, 13.5ft by 7.5ft, each supplied with a 6ft by 3ft wooden slat bed and ventilated by a barred 3ft by 1ft grate. Here was a "huge, practical reformatory" that would carry the work of the Andaman Islands' authorities into a new age. Every arrival would be forced "to bend his rebellious nature to the yoke"; Carnac Temple promised them a fate "even more dreadful than the hangman's noose".

It was not just the prisoners who suffered. From the inception of the project, the indigenous inhabitants of the islands, who had migrated on the trade winds from Africa at least 30,000 years before, acted out "a pantomime of defiance", emerging from the impenetrable jungle only to rain down arrows on British settlers.

In 1863, island chaplain the Rev Henry Corbyn, a graduate of Jesus College, Cambridge, had captured 28 Andamanese, 10 of them children, and held them hostage at the authority's headquarters on Ross Island. He wanted to "restore them to a place in the human family" and teach them to respect the British. The patrician cleric wrote in his journal of how he took eight "scientific curiosities" on a tour of India and Burma.

Only a small entry for the following month reveals what happened to the women and children left behind. "They appear," he wrote, "to have been assaulted, suffered the unwanted advances of a naval rating in charge."

By 1866, the penal colony's authorities recorded that the Andamanese tribes were "dying in large numbers". By 1870, the cause was found to be syphilis, introduced by the rapist. Eight years later, after measles, flu, tobacco, opium and whisky had swept out of the European settlement and into the jungle, more than half of the 5,000-strong tribal population was dead.

Vinayak Savarkar was aboard the SS Maharaja which docked on July 4, 1911, bringing prisoners to the brand new Cellular Jail. The wooden ticket around his neck declared that he was here to serve a 50-year double life sentence. "I felt that I had entered the jaws of death. The high wall was adorned with a festoon of manacles and several similar instruments of torture were hanging down from the wall," he wrote.

Prisoners in chains were equipped with two blankets, a kurta and tar-covered pisspot balanced on their heads. Before them stood the jail overseer, "a stout, corpulent Irish officer, carrying in his hand a big stick".

Savarkar scratched out his story with a nail on to the walls of his cell (No 52, Level Three, Yard Seven Wing. It had a view over the gallows that could hang three men simultaneously). Five years previously, in 1906, Savarkar had been admitted to chambers in London. It was at a time when India was on the cusp of another mutiny. The 50th anniversary of the Lucknow massacre loomed and Lord Curzon's decision to partition Bengal was threatening to destabilise the province. Savarkar, aged 23, took digs in a student hostel in Hampstead; he found it had become the headquarters for the newly-formed Free India Society. He turned his hand to translating Russian bomb manuals, and hollowing out copies of The Pickwick Papers to be filled with guns for India.

The smuggled munitions found their way to student activists such as Indu Bhushan Roy. Others - like Calcutta student Ullaskar Dutt, who stole chemicals from his father's university laboratory - made their own bombs. In the summer of 1907, the newly armed undergraduates combined forces in an abandoned bungalow in the city's rundown suburb of Maniktola, which was now a revolutionary school run by Barin Ghose, a dilettante born in Upper Norwood.

The following spring - April 30, 1908 - one of Ullaskar Dutt's home-made bombs exploded inside a carriage in Muzaffarpur. Instead of assassinating Douglas Kingsford, the chief presidency magistrate, as intended, they killed his bridge partners, Mrs Pringle-Kennedy and her daughter, Grace. Within days, the CID, Britain's fledgling foreign intelligence service, threw a dragnet over Bengal and began arresting the garden conspirators.

Meanwhile, in London, on July 1, 1909, Sir William Curzon Wyllie, political aide de camp to the Secretary of State for India, was gunned down on the steps of the Imperial Institute. Vinayak Savarkar, who had been sending arms to the Bengali student revolutionaries, was accused of providing the weapon. He was deported to India and then transported to the new Cellular Jail, where he found himself incarcerated alongside Prisoner 31549, Barin Ghose, Prisoner 31552, Ullaskar Dutt, and Prisoner 31555, Indu Bhushan Roy.

They recalled how every day, from 6am, David Barry would sit puffing on a cigar, watching them yoked to a press that they turned until they had produced 30lbs of mustard oil. And if the college boys fell sick, there was no sanctuary in the prison hospital, where a new recruit, Dr FA Barker, certified patients fit for flogging.

Shortly after 2am on April 29, 1912, the alarm went up on Yard Three Wing. Warder Gulmir had shone his hurricane lamp through the barred door of cell 82 and found an empty bed: "I saw the deceased hanging to the window." It was another six hours before Barker, the prison doctor, arrived.

A telegram giving news of the death was intercepted by Bengali revolutionaries. They published it on the front page of their newspaper, the Amrita Bazar Patrika. Indu Bhushan Roy, they said, had hanged himself with a strand of torn kurta, "exhausted by the unrelenting oil mill".

"I lay on my bed, my eyes riveted on the barred window," Savarkar scratched on his cell wall. Down the corridor, "troublemaker" Ullaskar Dutt was hanging by his wrists from a peg hammered into the wall above his head, one day into a seven-day punishment for accusing Dr Barker of aiding Roy's death.

Savarkar was the first to hear the cries on June 15 as warders dragged Ullaskar down the Yard Five Wing. "Ullaskar Dutt's gone mad," the shout went up and, according to his log, Dr Barker was waiting when the patient arrived at the jail hospital. He used a device to check if the prisoner was acting up. "I could feel the metal clips and then his battery playing on my body. The electric current passed through me with the force of lightning," Ullaskar would recall many years later.

News soon reached India, and in a police archive in Calcutta we found a flurry of despairing letters sent to "His Excellency the Viceroy" by Ullaskar's father, Dvijadas Dutt, a retired professor of agriculture. "It would afford both me and my wife great relief if you would be so kind as to enlighten us on some points: when, how and why did our son go mad?"

Eight more letters from Dvijidas Dutt followed, and then one brief reply from Lt Col HA Browning, chief commissioner of the Andaman Islands. "Patient's insanity is due to malarial infection. His present condition is fair." The next day, Ullaskar Dutt was transferred to the island's lunatic ward at Haddo. He would be held in an asylum for 14 years.

That some members of the government were now concerned by the Andaman Islands' regime is evident from a handwritten letter sent in June 1912 by Harold Wheeler, Secretary to the Government of India, to Sir Reginald Craddock, Home Member, Governor General's Council. "I am inclined to think that the punishment of standing hand cuffs is brutal and it would be well to inquire the desirability of its continuance." But Sir Reginald was having none of it: "Handcuffing to a staple is in my experience as effective on the recalcitrant as flogging. It undoubtedly causes great discomfort but Ullaskar Dutt is nothing more than a murderer and it seems to me a mistaken indulgence that he was not hanged."

It would be a hard line sustained for another eight years. Finally, in 1921, the Indian Jail Commission concluded that transportation to kalpani was "demoralising and unreasonable", and after pressure on the government transportation to the Andaman Islands was abolished in 1922. It was too late for Prisoner 38360, Chattar Singh, who had been suspended in an iron suit for three years. Too late also for Prisoner 38511, Baba Bhan Singh, who had been beaten to death by David Barry's men, and for Prisoner 41054, Ram Raksha, who had starved himself in protest at the removal of sacred Brahminical threads from around his chest.

Haripada Chowdhury bangs his fist on the table, scattering shortbread and grandchildren. "It was a gift to us Indians: 62,000 of us gave up our lives in world war one. That's why you said you'd close it down," he snorts. "But we had no time to say thank you. Tens of thousands of young men became ensnared in your emergency laws, and before we knew it you had changed your mind." On July 13, 1932, Sir Samuel Hoare, Secretary of State for India, announced in the House of Commons that political prisoners were once again to be transported to the Andamans project. "You resurrected kalapani," Haripada snarls. "Anyhow, how the devil did you find me? I haven't talked about these matters for many, many years."

Haripada was a 17-year-old Calcutta student in the winter of 1929, seditious leaflets raining down on his head. "It seemed as if the entire province was on the run or in prison," Haripada tells us. "Then my orders came. Silence Alfred Watson. I got hold of a pistol. My comrade was the shooter." On October 15, 1932, they cornered Watson who, as editor of The Statesman, had called for all terrorists to be hanged. "One shot winged him. Charles Tegart's men found me. Hiding at the safe house, 7/28 Telipara Lane. Before I knew it, I was locked in the SS Maharaja's pens."

It was June 1933 when he set sail, and Haripada knew that he was steaming towards a devastating hunger strike in which three men drowned in milk and dozens more had catheters forced down their throats. On the top deck of his boat was Dr Barker, the jail's former medical superintendent. (We found evidence of the doctor's intentions among the New Delhi files. "Recommendation of FA Barker, to Secretary to Government of India, 20 June 1933: If the medical authorities can be assured of immunity they should be given absolutely a free hand.") "We landed. Barker ordered us to strip." We can now barely catch Haripada's stuttering voice. "Soldered us into crossbar fetters." In his mind, the 88-year-old is now locked into heavy cuffs, his legs forced apart by a one-and-a-half foot iron rod that made standing almost impossible. "Then the doctor took away our drinking water rations. Three more inmates collapsed unconscious. No more to say now," he says. "Find Bankim Chakraborty - if he's still alive."

Bankim, when we tracked him down, was almost too sick to talk. Hauling himself to the edge of his chair, he grips the table with one hand as he palms away his son-in-law with the other. "I just got out of hospital. Lungs bust." He bangs his chest with open hands. "Haripada sent you? Okay, I'll tell you this much." We draw closer.

"I was a 19-year-old student in the north-east of India, when I was recruited to Jugantar, the covert New Age society. We could have licked the boots of our rulers and prospered, but I chose to fight and I'm glad that I did," Bankim says. "I could repair any weapon. I was carrying two pistols when I was caught after a post office hold-up. Shot me in the leg to slow me down. Case was heard inside jail. Sentenced to 15 years' transportation."

He sips on hot sweet tea and then launches off again. "I had been in an Indian prison for a year, but it was like a Begum's palace compared with the Andaman Islands. I arrived with Haripada and the hunger strike was in full swing. It would go on for 46 days in all. We only stopped after Dr Barker persuaded us that we had won. No more torture or the oil press. We would get bed sheets and mosquito nets. Fish for dinner. It didn't take long for us to realise that Dr Barker had lied. Three men had died and nothing was won. You promised us concessions and gave us nothing."

Silence fills the room. "We started dying. Fever. Dropping off, one by one. Now doctors Barker and Todd refused to treat us. They pushed the men to the edge of madness. Tied us naked to a frame. I was trussed up out in the yard. Flogged until our skin split. Or we were half-drowned, bound like chickens and dunked in salt water until I was gasping." Bankim cups his hands over his head. "Standing handcuffs. In 1935, I was hung for weeks at a time from a peg, high above my head, my face pressed against the bricks. So many things. Every day the Tommies swinging their lathis."

We show him an entry from the New Delhi files. "Major LH Marshall Upshon, Superintendent, Cellular Jail, to Chief Commissioner, Port Blair: I have the honour to forward herewith proceedings in the case against P.I.97 Chakraborty for assaulting Dr Todd, medical officer, with a shoe on the 12th inst. I have awarded him 20 stripes. Recommendation of Dr Todd to Major LH Marshall Upshon regarding punishment: Convict malarial. Too ill to be flogged. Suggest seven days in cross-bar fetters."

Bankim Chakraborty rubs his ankles: "I had nothing to lose, you see. I had read my history and I thought you would never let us out alive."

It is Bimal Bhattacharjee who fills in the missing years, although when we find him he is fighting for breath, gripping his wife's hand when he recalls his past. "I swore an oath over the Bhagavad Gita," he says. "If asked to lay down your life you will have to do so. I survived for only three years on the streets before Charles Tegart's men caught up."

The 89-year-old's chest rattles as he places a finger before his lips. "I said nothing to my captors." And around us, at every window and door of his ground-floor bedroom, neighbours and second cousins now strain to hear. "Beaten up. Taken before English magistrate Johnson. No evidence, but transported to the Andaman Islands in August 1936. I was sailing towards a holiday camp, according to the British papers. I had nothing to fear, the British authorities said."

On April 28, 1936, Sir Henry Craik, Home Secretary to the Government of India, finally visited Port Blair after persistent rumours of torture and brutality were published. Sir Henry listened for days to the inmates' complaints before filing a report to Simla. The penal project was "a prisoner's paradise".

Bimal sinks into the bowels of his bed. "I arrived at the Cellular Jail and men were dying on their feet: dysentery, TB and malaria. We got up a petition, 239 of us," he says. "Doctors made this penal colony and they decided to break us. There was no response to our petition. We called another hunger strike on July 24, 1937. Three days in, a tube was forced down my throat. I was terrified. You cannot even imagine it. Remember that we all knew about Mahavir Singh. But soon there were 230 men refusing food. We were in a desperate state. The news spread like fire through Bengal. The country was behind us. We were on the verge of death and a telegram arrived on August 28 from Gandhiji himself."

"Nation-wide request to abandon the strike... trying best to secure relief for you. MK Gandhi."

It was on September 22, 1937, that Bimal and the first group of prisoners were repatriated. The Cellular Jail was forced to empty in 1939. Two years later, the Japanese seized the islands, transforming the penal settlement into a prisoner of war camp, incarcerating the British warders. In 1945 the Andamans would become the first piece of India to be declared independent.

"You cannot even imagine it. When our ship entered Diamond Harbour, we breathed so deeply. No one could quite believe that we had come back across kalapani." The humid bedroom collectively exhales. "But it was too late for many of us, we had lost so much. Who knows of these things any more?" Bimal cocks an accusing finger that takes in the whole room before stopping at us. "It's your black water, you should cross it now."