"The reason Vivian Bullwinkel did not come clean, which she intended to do before her death, was because she was ordered when she was still in the army, not to include these details in her depositions to the Tokyo war crimes tribunal." The only other reference to violation was taken out of archives and destroyed because it never went to trial, she said. They said to me on several occasions there are some things we have agreed to never talk about, but they wouldn't say what it was. Lynette Silver, historian Sixty-five Australian nurses were evacuated from Singapore before it fell to the Japanese in February, 1942. Their ship, the Vyner Brooke, was bombed and sank, with 22 nurses reaching Radji beach on Banka Island, Sumatra. They were later joined by 25 British soldiers. When Japanese soldiers arrived, the men were taken aside and murdered and the women were marched into the water and machine-gunned. As they were prodded with bayonets into the water, Sister Esther Stewart called out: "Girls take it, don't squeal."

Sister Bullwinkel, who was wounded, was the only survivor. "I was towards the end of the line and the bullet that hit me struck me at the waist and just went straight through," she later told the War Crimes Board investigators. The waves washed her back to the sand where she remained for another 10 minutes before she got up, the Japanese having disappeared. The question re-emerged in 1992 and 1993 when two Japanese academics with access to documents released by the Japanese government floated the possibility that nurses captured on Bangka had been raped. Vivian Bullwinkel, the only survivor of Radji, and her uniform showing the exit hole of the bullet. Raising more questions than answers was a 10-page report in the National Library of Canberra written by Jean Williams, wife of Major Harold Williams, about investigations he conducted for the Australian War Crimes Section.

Her account includes his investigation of the murder of the nurses. Examining it, Silver discovered the nurses' narrative stopped mid-sentence. Writing in Angels of Mercy – which is published on Monday – Silver states: "There was nothing more on the next page. Mrs Williams' narrative had continued overleaf, but someone had crudely hacked off the top five centimetres with a pair of scissors. "It was evident that whatever else Mrs Williams had written about the nurses had been removed by someone determined that no one else should see it." A previous examination had been made of the pale-grey uniform that Bullwinkel was wearing when she was shot which is held at the Australian War Memorial. The nurse always maintained that the bullet had passed through the flesh just above the hip. The problem was that the bullet entry and exit holes didn't line up. Examination by Professor John Hilton at the Institute of Forensic Medicine in Sydney had concluded that had the bullet followed that route if the uniform was buttoned up the victim would have been 'severely incapacitated'.

Uniform Vivian Bullwinkel was wearing when she was shot. Credit:Australian War Memorial The carer who looked after Bullwinkel, who died in 2000, confirmed entry and exit scars, though very faded, were 'almost together on the left-hand side of Vivian's torso'. Biographer Barbara Angel, who had written the story of another POW nurse, Wilma Oram, found that by undoing the buttons of a similar garment and pulling the open bodice back, the entry and exit bullet holes became aligned. She also found that most of the buttons on the uniform were sewn on with matching thread. The two on the bodice, however, were sewn on with aquamarine thread, indicating that the uniform bodice was ripped open so forcefully that the buttons were torn off and lost, making it necessary to replace them with the two missing from the bottom two places on the skirt. "There was no doubt about it. Vivian Bullwinkel had entered the water with her bodice undone and open to the waist," Silver writes.

Bullwinkel said she would speak out but she took her secret to the grave. Almost. She had spoken confidentially to broadcaster Tess Lawrence. In an online article she wrote Bullwinkel was tortured by the secrets. She confirmed she and the other women gunned down had been violated beforehand by the Japanese soldiers. "The second matter related to this violation and it more than irked her," wrote Lawrence. "She had been ordered by the government not to say anything about the rapes. She wanted to put this in her statement before the war crimes tribunal but was ordered not to by the Australian government." Silver said if she decided not to write the book she could be added to the long line of people covering the story up. "It did happen. The nurses did suffer in this way and to ignore it is to deny their right to have the truth actually told all these years later. The only people I would be protecting are the perpetrators.