Johann Hari: How can we trust an army that cannot be trusted with its own?

All attempts to get a public inquiry into the Deepcut deaths have been stonewalled

Over the past fortnight, there have been torrents of emotional tributes to British soldiers from our politicians – and they are all hollow. Yes, they meant it when they expressed sorrow at the young men murdered in Northern Ireland. Yes, they were genuinely repulsed when welcome-home military parades in Luton were disrupted by Islamists who glorify the Taliban. But the purple patches of praise for "Our Boys" – and the long list of fallen soldiers that now opens every Prime Minister's Questions – seem vacuous when you remember a stark fact, exposed once more this week in the important new play Deep Cut at London's Tricycle Theatre. These self-same politicians are still refusing to investigate the highly-suspicious deaths of British troops – even though they were almost certainly killed by a culture of sadistically humiliating and hurting our soldiers.

As most people now vaguely know, between 1995 and 2002, four young recruits to the Army were found dead at the Deepcut Barracks in the rolling English countryside, where they were supposed to be undergoing training. Two of them were just 17 years old. The Army swiftly ruled that they were suicides. It is now clear that the truth is much more complex – and dark.

This is not just a matter of history. As you read this story, keep asking yourself one question. If the British Army reacts to the death of its own troops in the open air in the middle of Britain with such reflexive indifference and elaborate cover-up, what are they doing in Helmand province, or Basra, when civilians there are abused?

Here's what we know. More than 1,000 young recruits passed through the Deepcut Barracks, near Camberley, Surrey, every year. Many of them were just 16, many of them illiterate and from the moment they arrived, they were inducted into a culture where they were forced to participate in extreme and bizarre acts: being thrown out of a window if their locker was untidy, being pissed on by officers, being made to swim through a cesspool. One female private was forced "to run around the parade ground naked wearing a belt with mess tins attached to it"; another was ordered to get out of the shower "naked and wet" and made to go on parade with other soldiers at the height of winter. A racist gang called "the Black Card Club" would inform an ethnic minority soldier he had been selected "for a beating" by leaving a card with a white cross in their locker.

It has finally emerged – after all this time – that there have been more than 100 allegations from terrorised recruits, including of at least one gang-rape. Female recruits were told they could have an "easier life" if they "consented" to have sex with large numbers of men. One corporal already convicted for predatory sexual behaviour towards teenage boys was posted to the Deepcut gym, where he forced young soldiers to participate in canings and sex. When soldiers protested, they were told to "stop being a poof".

Former recruits have subsequently started to come forward, and one says: "No one knows how many were attacked, but everyone knew it went on ... horrible [sexual] things went on involving groups of officers and it is difficult even thinking of it now. Many women ended up in psychiatric hospitals." It's an Abu Ghraib at the heart of Britain – inflicted by troops on troops.

This is the context in which four young recruits were found shot dead. There are two possibilities. Either this culture drove them to suicide – or it escalated to the point of murder. Whichever is the case, the army hierarchy didn't want to know. They prioritised avoiding an embarrassing fuss over finding out the truth.

The play Deep Cut focuses on one of the victims: Private Cheryl James, a bubbly 17-year-old Welsh girl. Her body was found in a foetal position with a gun neatly by her side one night in 2002. Despite the fact this was the third suspicious death in the same place, the Surrey Police investigation assumed it was a suicide from the start. They barely interviewed relevant witnesses, and even the bloody shirt in which one of the victims was found was sent away to be washed clean.

Since then, her friend and fellow Deepcut soldier Mark Beards has come forward to say that on the eve of her death, Cheryl was given the choice of becoming a sex slave to a clique of bullies or facing trumped-up disciplinary charges. Did this drive her to kill herself – or was she punished for refusing? Her family's attempts to try to secure an investigation were treated with contempt by the Army, who refused to even return their calls for months on end.

The BBC's Frontline Scotland programme asked Frank Swann, one of Britain's leading forensic experts, to study the evidence. He explains: "After spending six weeks conducting a serious forensic study and tests ... I am satisfied [they] were in fact murders." Private Sean Benton, 20, was found with five shots run through his body, but the gun that killed him – the SA80 – fires between 650 and 700 rounds a minute on automatics. So Swann says: "You could not reproduce that pattern on Benton unless you were 14ft away. That means Benton would have needed arms 14ft long to shoot himself." Similarly, Private Geoff Gray was found with two deadly shots to the head – in different places. Swann says: "It can't be done."

All attempts to get a public inquiry have been stone-walled. The Government asked Nicholas Blake QC to look into it, but didn't give him the power to compel or cross-examine witnesses, producing a farcically empty report. There appears to be no determination to root out this culture and make sure it never happens again. So let's go back to that early question: if military personnel treat each other with sadism and a culture of impunity even for murder, how are they treating ordinary Afghans and Iraqis? This is not just a matter of justice – it is a matter of national security.

Soldiers need fitness, discipline and preparation for life under extreme pressure – and yes, some of that preparation will be gruelling. But they don't need extreme cruelty. Indeed, if our troops are being primed to react to circumstances of stress – or even everyday life – with ritualised humiliation and reflexive violence, then we will all be less safe, because we will be hated even more wherever they are sent. The Army is supposed to be a public service meeting our needs, not a self-serving, self-preserving clique covering up crimes by its own.

Even the neutered Blake inquiry demanded that the Government establish an independent body to investigate allegations of abuses within or by the Army. They refused. But far from hindering Army efficiency, over time independent investigations will massively increase it. Compare it to your own life: would you do your job better or worse if you knew nobody was ever going to check you were doing it right or investigate your mistakes?

Ever time you hear a politician pouring out platitudes about how much they respect and revere Our Great Troops, snap back: so when is the public inquiry into the killing of soldiers at Deepcut starting then? Unless they give you a date, you can be sure they are lying.

Johann is interviewed on the latest Drunken Politics podcast about Palestine, piracy, and what makes him happy. Part One is here. Part Two is here .

j.hari@independent.co.uk