Even with the thick, almost opaque, goggles he had been given, Derek Allen could see the flash of the atomic bomb as it exploded 15 miles away. It was so bright that he saw all the bones in his hands as if he were holding up an X-ray. He was 21, a long way from home and terrified. Sitting in his khaki shirt and a pair of shorts, with his back to the blast, the young soldier hugged his knees close to his chest and braced himself for what he had been told would come next - the searing heat from the nuclear explosion.
"It felt like someone had opened an oven door behind you," he recalls. "It went right round your body and inside your guts. I had never been so frightened."
But it wasn't over yet. Next came the blast, so strong that it lifted Derek and shoved him to one side with the force of an invisible punch. Then he turned around and saw his first mushroom cloud, snaking thin and beautiful up into the atmosphere behind him. That was the first of 24 nuclear explosions to which Derek, now 68, was exposed in less than three months. It was April 1962 and he was taking part in atomic weapons tests, the medical effects of which would not become clear until years later.
After decades of campaigning by veterans, and shameful prevarication on behalf of successive governments, the nuclear test guinea pigs have made significant progress in recent months towards receiving the compensation and war pensions many argue they deserve. In January, the first leg of a test case began at the High Court in which 900 veterans and their widows are suing the Ministry of Defence for negligence. Then, last Tuesday, Defence Minister Kevan Jones announced in the House of Commons that the Government is launching an inquiry into possible links between the severe illnesses suffered by service personnel and their families and the tests they took part in.
Some 22,000 British service personnel witnessed such tests between 1953 and 1963 in Australia and on Christmas and Malden Islands in the Pacific. There were also around 330 British troops seconded by the Ministry of Defence to take part in American testing off Christmas Island in 1962. Derek was one of them. He welcomes the inquiry, although for him the news is bittersweet. "I'm really pleased for the British veterans and I hope it comes out in their favour," he says. "It's very good news but I'm not sure it will help me because I took part in American testing. We were involved in many more bombs than they were."
While hope may be on the horizon for British veterans who took part in Britain's tests, Derek has been left in limbo. He is not part of the current High Court action, and does not qualify for compensation from the US Government. He remains convinced, however, that what he experienced in the Sixties has had far-reaching consequences for himself and his family.
"As servicemen, we'd heard the word ‘radiation' but we didn't know what it really meant," says Derek, who lives in Sussex. "We were so naive. In the 24 hours after each explosion, some of the men felt sick. I didn't, but I remember being sick with apprehension each time they told us there was going to be another one."
Within a few years many of the men had developed cancers and the rate of miscarriages among their partners grew to alarming levels. Evidence is now growing of damage having been caused to their DNA, damage which may have resulted in gene mutations that caused illnesses and congenital deformities among their children.
In research conducted by the independent environmental consultants Green Audit in 2007, the rate of congenital deformities among nuclear test veterans' children was almost ten times higher than that of an average control group. Among veterans' partners, the rate of miscarriage was three times the average.
In 1965 Derek's first wife miscarried a baby boy. Then came relief with the birth a year later of Dawn, the first of three daughters. She seemed perfectly healthy for a while; then it became clear that she had difficulty walking. When she was 4, muscular dystrophy was diagnosed. This is usually an inherited disorder that causes a slow wasting away of the muscles, but there was no history of it in the family. Baffled doctors changed the diagnosis a number of times until, at 24, a series of MRI scans revealed that the insulating sheaths around Dawn's nerves were waterlogged. Doctors said that there was no formal name for her condition.
Today, at 42, her illness remains formally undiagnosed. We meet at her small flat on the South Coast. She is bedridden, paralysed on one side after a recent series of strokes, has difficulty speaking and is totally reliant on her husband Steve. She is obsessed with everything Disney and is wrapped in a Winnie the Pooh quilt. All around, to help her imagination to roam beyond the confines of her bedroom, are DVDs and videos.
"I can't help thinking that the radiation my dad was exposed to had something to do with it," she says. "I'm not angry but I do wish someone would admit that what happened to my dad was wrong, and stand up and say sorry."
So, could Dawn be right? Could exposure to radiation be passed on as deformities to one's children? The answer, according to research conducted into the children of those exposed to high doses of radiation at Hiroshima, Nagasaki and Chernobyl, is yes. But can Dawn's family prove it? The answer - a response that plagues all such possible victims - is no, not medically and certainly not as an individual.
According to Kit Hill, former Professor of Physics at the Institute of Cancer Research, there are so many environmental factors that surround us that it is virtually impossible to pin the cause of an illness on any single one of them (and we are all exposed to small doses of background radiation every day, from sources such as cosmic rays and luminous dials). "There are a number of conditions that run more strongly in some families than others," says Hill. "And in genetically-influenced conditions like that, the likelihood of them happening increases to some extent by a parent having been exposed to radiation. The difficulty is that, as far as I know, no one has ever established a one-to-one relationship between exposure to radiation and a pathological disease of any sort."
Hill says that with rare conditions such as Dawn's, the temptation is for a family to assume that some extreme cause, such as her father's experience, was to blame. But proving it medically would be impossible and attempts to pin down the cause statistically would equally be stymied by the fact that her condition is so rare. It is only when large numbers are involved that assumptions can be made. Which is why the British Nuclear Test Veterans Association (BNTVA) commissioned Green Audit to canvass its members and find out about the health of their children. The researchers, led by Chris Busby, visiting professor at the Faculty of Life and Health Sciences at the University of Ulster, gathered information on just over 600 children and 749 grandchildren of veterans and, for comparison, 718 children of non-veterans. The results were nothing short of terrifying. When expressed as cases per thousand, the children of veterans rated 94.2 for congenital defects such as vital organs not being formed properly and hands having extra thumbs, compared with 9.6 in the non-veterans' group. Among grandchildren the figure was 61.4 compared with 7.4 per thousand.
One veteran suffered sunburn and diarrhoea after a test explosion. His child suffered "growth problems from the age of 5. Skeletal and skull slow growth giving brain damage symptoms". Another man reported bleeding gums, deafness and a flu-like illness after a test. His child has Down's Syndrome. There are children with spina bifida, a girl with no ovaries, one with an extra pocket in a bladder, hip defects, heart murmurs, blindness and deafness, all at rates that appear to be well above the national average.
The Green Audit report concludes: "What we seem to see here is a similar effect to that which has been reported in the Chernobyl-affected territories, namely the transgenerational induction of genomic instability, a process where a signal is passed down to the offspring which causes increases in random genetic mutation." Asked to explain this, Busby says: "It is as if the genes in the group, exposed to extreme exceptional circumstances, are throwing up random mutations in the hope that one of them might help the group to survive."
I ask him if Dawn's symptoms may have been such a random mutation. He asks about her father's exposure and, when I tell him about the 24 tests, he says: "My God, that man must have been exposed to so much radiation. If you're asking me whether there is a case for arguing that [Dawn's] condition could have been caused by her father's exposure, I would have to say yes."
Other pieces of research, most notably by Dr Al Rowland of Massey University in New Zealand (its forces were also exposed to tests), have indicated that genetic damage to DNA has resulted in deformities in children.
In the US, the Radiation Exposure Compensation Act was passed in 1990, sanctioning payments of $75,000 for exposed veterans, but ex-servicemen may make a claim only if they have one or more of 21 accepted cancers. In 2006 Roy Prescott, who had lung cancer, became the first British soldier to receive payment from the US Government. He died two months later. Derek has had many health problems, including two heart attacks, panic attacks and lumps on his hands and arms, but he has no cancers. In that respect, he is lucky. But as things stand, his claim against the Americans would fail and no one is helping him to claim against the British Government.
In 2007, he was advised by solicitors acting for the BNTVA that his claim fell outside the remit of their group litigation. This is significant because when the High Court litigation reaches its conclusion, secondary action will take place on behalf of the children of the veterans, and that will exclude children such as Dawn because her father took part in the American tests.
"I feel as if those of us who took part in the American tests have been left behind by our comrades," says Derek. He resigned from the BNTVA after he had to drop his claim. Douglas Hern, the association's litigation secretary, says: "Apart from Mr Allen, we have only ever heard from one other of this group [British personnel who took part in American tests], a man living in America who we have lost touch with. I sympathise with Mr Allen, but long ago we were told to concentrate on trying to help British veterans affected by British bombs in British tests."
Two years ago, two MPs, Ian Gibson, of the Labour Party, and the Conservative John Baron, set up an informal inquiry in the House of Commons. It concluded that the new evidence did indicate a link between the exposure to radiation and the illnesses among veterans' children.
"These men have been treated extremely shabbily," says Gibson. "Successive governments have been dodging their responsibilities while families have been suffering. The MoD's denial of a link between nuclear tests and ill health looks increasingly shaky now that children and grandchildren of veterans are experiencing congenital disease and early death." Gibson and Baron's efforts led to last week's announcement of Government-backed research.
Only a small number of people have seen the mushroom cloud from an atomic explosion close up. Most of them are dead. Those who survive endure not only their own awful ailments but must, in many cases, wince and weep while their children and now grandchildren suffer before their eyes. As Derek Allen says: "When we realised that we had been put in harm's way by our country, that was bad enough. But we never dreamt our country would turn its back and forget all about us."