From the Isle of Dogs to Helmand Province

Three seriously injured men are carried into the hospital on stretchers; two bloodied British troops and a bearded Afghan, his shirt ripped open screaming in a foreign language.

One of the soldiers is unconscious the other shivers, blood spurting from his leg; his foot is detached below the knee and rests on the stretcher, still in its boot.

The grim procession of injured and dead continues to pass for twenty minutes.

It is a macabre scene but fortunately, for now, it is fake.

The sound of the helicopter is a recording and the casualties are actors in elaborate make-up, including amputees and 'afghans' hired for the weekend training exercise.

But that all changed on Tuesday when nearly 200 NHS staff - members of the Territorial Army's 256 Field Hospital - swapped the cavernous hanger in Strensall, Yorkshire, for Camp Bastion in the heart of Taliban territory in Helmand, Afghanistan.

"We're going to see a lot of traumatic injuries - amputations, serious burns caused by IEDs (improvised explosive devices)," says Captain Sian Page, 28, of Blackwall, Isle of Dogs, who in civilian life is a sister in London's busiest A&E department at the Royal London in Whitechapel.

"In London we see a lot of blunt trauma type wounds caused by stabbings, falls that kind of thing. But we're prepared to treat very different, and more severe, injuries out there.

"We'll also treat locals, including children and some Taliban fighters who are brought through the door."

This summer Camp Bastion's field hospital has treated some of the worst injuries inflicted since the start of the 2001 conflict in Afghanistan.

Over 80 soldiers have been killed in operations since the start of 2009 and around 100 admitted to the field hospital in the most serious conditions, the majority after stepping on IEDs laid by the Taliban.

The result can require double or triple amputations.

While they may not have encountered similar injuries before, 256 medics are all already highly skilled surgeons, nurses, consultants and other hospital staff serving the NHS across London and the south-east.

The object of the Strensall exercise is to test their teamwork, not clinical skills.

Divided into departments the hangar is a scale representation of the medical facilities in Camp Bastion, where the International Security Assistance Force (ISAF) forces receive round-the-clock 'gold standard' care.

The mock-up is well regarded by the US military who send their Naval medics to Strensall for pre-deployment training.

"There's nothing like this in the U.S," says US Navy Lieutenant Commander Gregg Gellman.

"It brings the different units together and helps us bond and learn the differences in how we work... and speak."

In Bastion the medical expertise is so good that there are reports of 'miracle survivals' - horrendous multiple amputations which would have resulted in death just a decade ago.

Over their three month deployment the staff from 256 will hone their skills in handling traumatic injuries.

Capt Page, who has been in the TA for six-and-half years, hopes to pass those skills onto the NHS on her return.

"I'm sure I'll learn things I can bring back. The care for trauma at Camp Bastion is about as good as you will find anywhere," she says.

The care will extend to local Afghans - including the Taliban - who as the Ministry of Defence lines say have come into 'contact' with British forces.

It means British medics may be asked to carry out life saving surgery on the enemy, perhaps the same person who has planted an IED or shot British troops.

The Geneva Convention binds the army to that commitment, but several conversations suggests that saving the enemy at times sits uneasily with the 256.

"We're human beings and everyone has an opinion on that," says Corporal Kevin Cairney, 28, diplomatically.

"But as medics we also occupy the moral high ground in a way - we will treat everyone equally, we're there to do collateral goodness."

There is a mixture of excitement and trepidation as deployment nears, with the reservists aware that the gruesome injuries and relentless hours in the desert camp will be a gruelling test of their skills and temperament.

All will miss family and friends over Christmas, but the camaraderie on display in Strensall will go someone to filling the gap.

"I am nervous, it's a big personal test," explains Capt Page. "I don't know what I'm going to face. It's a huge test of my skills and experience.

"But we've trained hard for this and I just want to get out there and get to work."

Photos by Matt Grayson