It is one of the few genuine issues of life and death during this general election campaign. It will not dictate how much any British school improves, how many police appear on the streets of a city, or how quickly patients are allowed to leave hospitals around the country. But it will, literally, decide the fate of thousands of British service personnel and, ultimately, how many of them live and die.

A British soldier stands guard during a patrol in Qari Saheb village in Helmand province. (Photo: The Independent) Yet nobody wants to talk about Afghanistan.

When Nick Clegg "won" the televised party leaders' debate on Thursday night, his victory owed nothing to his limp response to a question about support for British troops serving in Afghanistan. The Liberal Democrat leader agreed that British troops in Afghanistan were under-paid and under-equipped, but he did not question why they had lost 281 colleagues in that country, or why they were there in the first place.

Similarly, Gordon Brown and David Cameron have pledged loyal support for a campaign that is deep into its ninth year, and shows no sign of nearing an end. In front of the cameras, the Prime Minister offered sombre reflection on the campaign, while Mr Cameron queried the number of helicopters available to British forces. Yet neither has gone out of his way to tackle the issue head-on elsewhere during this campaign, to explain why the UK should remain in Afghanistan, why it should continue to support a discredited government in Kabul, and how many more British service personnel must die before the mission can be brought to a close.

Last November, The Independent on Sunday called for a "phased, orderly withdrawal" of British forces from the "ill-conceived, unwinnable and counterproductive" campaign in Afghanistan. The UK still remains in there - and more than 50 servicemen have died since then. Last month, The IoS revealed that Britain harboured profound concerns at the highest levels over the quality of the Afghan police who must guarantee security before our troops can leave.

The leaders may, at last, be forced to explain their positions this week, when the second debate concentrates on foreign affairs. But, given their performance so far, it is unlikely that they will offer any fresh hope for the service personnel in Afghanistan or their families back home.

"We want to see more substantive engagement on defence issues from the parties," said Douglas Young, executive chairman of the British Armed Forces Federation, an independent staff association for service personnel. "Up to now, there have been too many airy-fairy platitudes and not enough substance."

These are leaders who last week presented election manifestos amounting to more than 80,000 words on their grand plans for education, health, the economy, but who managed to mention Afghanistan only 19 times between them.

The stifling of the issue might be due to the fact that all the main parties know their policies are entirely at odds with the feelings of the population over Afghanistan. In November, a poll found that 73 per cent of people wanted British troops to come home within "a year or so" - and almost half of them called for immediate withdrawal.

A poll for The IoS today finds that this number has increased, with 77 per cent now supporting withdrawal on the same terms. The number disagreeing is now below one in seven. Further, more than 50 per cent of those polled believe that the risk of terrorism in the UK is increased by the presence of British troops in Afghanistan.

However, none of the major parties is promising to pull troops out if they get into government and only the Scottish National Party - confined to one part of the UK - is calling for an honest reappraisal of the operation. The Lib Dem leader, Nick Clegg, last week made much of his record of "speaking out pretty forcefully" on Afghanistan. But his manifesto commits the party to being "critical supporters of the Afghanistan mission'', albeit with a pledge to match the military surge to a strategy of tackling corruption and winning over moderate Taliban.

The Lib Dem defence spokesman, Nick Harvey, yesterday conceded that anti-war voters have few choices. "If they are against the whole principle of being involved [in Afghanistan], they'll struggle to find anyone putting that case," he said. For opponents of the war, the lack of differentiation between the three main parties and their failure to embrace the Afghan question during the first two weeks of the election campaign amounts to a "conspiracy of silence" to suppress debate.

Chris Nineham, of the Stop the War Coalition, said: "There has been a deafening silence about Afghanistan in the run-up to the election. The three main parties are doing their best not to mention the war, despite the fact that the vast majority of the population oppose it."

Yet, despite complaints from the most vocal critics of the war, there is no guarantee that, however strongly voters feel, they are prepared to treat it as an electoral issue. In November 2006, when the toll of British deaths during five years of the campaign stood at 41, pollsters Ipsos Mori found that "defence/foreign affairs/Iraq and Afghanistan" topped the list of concerns facing the country. Two out of five voters spontaneously identified it as a key national problem. Three and a half years on, with 240 added to the death toll - 36 this year alone - it has slipped to seventh.

A leaked CIA report last month observed how "some Nato states, notably France and Germany, have counted on public apathy about Afghanistan to increase their contributions to the mission". It also argued that such apathy "enabled leaders to ignore voters". It seems that Britain's leaders are banking on indifference to help them through a potentially troublesome campaign without having to confront the most troubling issue before them.

"All three parties in 2001 thought we should go in. There are no votes in it, so they keep quiet about it," said General Sir Hugh Beach, former deputy commander of British Land Forces.

Five years ago, public opposition to the Iraq War was widely listed as a contributory factor behind a general election result that cut Labour's majority from 167 to 66. And lingering rancour over the war helped to lever Mr Blair from office two years later.

Afghanistan has been different. It has been overwhelmingly regarded as the "just" war. It was portrayed as a campaign to democratise a wild nation, to oust the Taliban, al-Qa'ida and all the extremists threatening the West with terror plots over the past decade.

That justification has lost its power as the death toll spirals and Afghans show little inclination to take control of their own affairs. Military commanders in Pakistan, where suicide bombers killed more than 40 people yesterday, regard the failure of US-led forces to defeat the Taliban in Afghanistan with ill-concealed derision.

"They don't have the legitimacy we do," said Colonel Nauman Saeed, who commands 3,500 solders in Bajaur, a mountainous district on the Afghan border. "Afghans see them as illegitimate intruders and occupation forces." At the moment, the Pakistan military are in a victorious mood after retaking much of the territory along the Afghan border which was ruled by the Pakistan Taliban a year ago.

When experts point to terror plots from Pakistan and even within the UK, the Government's contention that the Afghan campaign is vital to protect Britain's security at home is difficult to explain.

And the government of President Karzai continues to raise concerns in Nato capitals. "The problem we have is that the regime in Afghanistan, which we support, is built on electoral fraud, with graft and corruption," said the SNP's foreign affairs spokesman, Angus Robertson. "We need to be absolutely honest about our options, and one of the aspects of that is that there needs to be a decision about when we bring our forces home."

The IoS military covenant panel

Major General Patrick Cordingley

"There is an embargo on the Ministry of Defence, so there is virtually no news coming out of them. The two main parties basically agree on Afghanistan. If somebody disagreed it would be a big issue but as they all agree, there's no point banging on about it."

Major Julian Thompson

"The reason is the parties have stayed off the issue in toto. Defence is unfortunately the last thing people think about and it is not something that turns people on. Labour got us in there in the first place and don't want people to be reminded of it."

General Sir Hugh Beach

"Nobody thinks there are votes in it one way or the other. All three parties in 2001 thought we should go in. There are no votes in it either way, so they keep quiet about it."

Rose Gentle, mother of Fusilier Gordon Gentle, killed in Iraq

"It isn't really a vote-winner. Iraq isn't mentioned and the soldiers that died there are the silent heroes. Families I've spoken to think someone should say something about it, but to be honest I don't think anyone will."

Retired Colonel Clive Fairweather

"In 2001 it was the war on terror, but since then the country can't make the connection with the war on terror any more. I don't think the Tories or Nick Clegg have much else to offer. It would only become an issue if there were multiple casualties, which is not very good for troop morale."

James Fergusson, journalist, foreign correspondent and author of 'A Million Bullets: The Real Story of the British Army in Afghanistan'

"It is easy to say we need more helicopters but I have always thought that the argument that we are fighting over there to protect the streets is easily shot down. But I think the [political] opponents are too scared to take on the issue."

The Rifleman: 'William would have made a fantastic husband and dad'

Anyone who met Rifleman William Aldridge had only to look at the teenager to know how much his family meant to him: he had the name of his young brother George tattooed on his arm.

He had planned to get Archie, the name of the youngest brother, inked on his other arm but was deployed to Afghanistan before he got the chance. He was killed, aged 18, by an IED blast while on foot patrol with the 2nd Battalion The Rifles in Sangin province on July 10. He now holds the tragic distinction of being the youngest British soldier to die in the conflict.

It took his mother Lucy Aldridge, 42, a couple of weeks to find the right words to tell his brothers - then aged five and four - that they would not see him again. "I explained that William was doing a very important job protecting people in another country but now he had a much more important job to do and that meant that he wouldn't be able to come home because he had gone to be with the angels and look after everybody."

William's brothers meant "everything to him. He would have made a fantastic husband and dad."

The rifleman was a "very keen outdoors type" as a child, enjoying martial arts, rowing and canoeing. He was a Cub and a Scout, and joined a rifles cadet force when he was 12, his mum said from the family home in Bredenbury, Herefordshire.

"It was his dream, so I couldn't have been happier with him knowing exactly what he wanted to do."

That dream saw him sign up at the age of 16 after taking his GCSEs at the Minster College in Leominster. He passed out in August 2008 after basic training at the Army Foundation College in Harrogate and moved to Catterick for infantry training. He joined his battalion in Ballykinlar, Northern Ireland, that December.

William, who had formed part of the rearguard looking after families of serving soldiers, was posted to Afghanistan three days after celebrating his 18th birthday on 23 May last year with a family meal.

In their last conversation he sounded in "good spirits" but also "extremely tired" after being at a patrol base for 10 instead of 28 days due to "an inability for them to be resupplied with equipment, with basics like water and ammunition".

Two days later, he was killed following an improvised explosive device (IED) blast during an early-morning foot patrol. The "calm" soldier helped comrades caught up in an earlier explosion in which he had also been injured. He was airlifted to Camp Bastion but died about an hour and a half later.

Ms Aldridge is calling for a ban on foot patrols "unless greater safety measures are put in place to protect these young men".

She has since thrown herself into fundraising, launching the Kilimanjaro 2010 Appeal in October. The project hopes to raise £40,000 for the Royal Centre for Defence Medicine patient welfare fund at Selly Oak Hospital and the Rifleman's Fund, supporting injured riflemen and bereaved families.

This October, she will officially launch the William Aldridge Foundation to raise money to support charities caring for wounded service personnel across the three armed forces. She wants to expand help "not just for the physically injured but those who are psychologically scarred", and describes the problem of soldiers suffering mental illness as a "ticking time bomb" that urgently needs government funding.

"I would hope that had my son returned home somebody would be doing the same for him," she said.

Kate Youde

The amputee: 'He never wavered'

At just three, Lance Corporal Simon Wiggins was inspired by his grandfather's interest in the Guards, and the pair watched Zulu together. Now 23, he is rehabilitating after stepping on an IED on 16 March 2008, while serving with the First Battalion Coldstream Guards in Helmand. The blast - two weeks before he was due home - necessitated the amputation of his leg. He also suffered extensive internal trauma and lost a finger. His mother, Gilly Wiggins, 50, of Coulsdon, Surrey, said his military passion never wavered during his childhood and "he used to go running with a backpack full of Coke bottles filled with water to train".

The sniper enlisted in 2004 after his A-levels and trained at Catterick, passing out in May 2005. He was serving in Iraq the following month.

But Mrs Wiggins, vice chair of a support group at the charity Soldiers, Sailors, Airmen and Families Association Forces Help, worried about his deployment to Afghanistan and had a "strange feeling" about it. Her son made a "miraculous recovery" and is now at the regiment's Aldershot base.

Kate Youde

The veteran: 'I was a mess. The Army didn't help me'

Lance Corporal Jim Maguire (not his real name), 29, from Hull joined the Army in 1998 and served in both Iraq and Afghanistan. He began to develop obsessive compulsive disorder (OCD), depression and anxiety in Iraq which developed into PTSD after he was ambushed in his Scimitar in a village in southern Afghanistan. "I was a mess. The Army didn't provide me with help. Fortunately I was referred to Combat Stress. They saved my life. I met other guys who'd been through it too. It was a massive help. It's easy to hide a problem. They hide people like me. "

Paul Bignell

The mother: 'I was glued to the news'

Diane Blackmore-Heal, a police officer from Banbury, near Oxford, welcomed her son, Adam, 22, home just two weeks ago after a seven-month tour with the Household Cavalry in Helmand province.

"Adam has wanted to be in the Army since he was five years old. This was his first tour of active duty, and I don't think I realised how stressed I was until he came home and I started to sleep properly again. I was glued to the news for seven months. Somehow I felt he would come back but I was aware of the IEDs and worried whether he would cope with a serious injury. Adam showed me a picture of a colleague, taken after he lost both legs on their last patrol; it could have been him."

Nina Lakhani

The parties...

Labour

Manifesto: 78pp, 30,227 words

Defence: 2,750 words

Health: 2,950 words, 47 mentions

Education: 1,927 words, 61 mentions

Afghanistan: 11 mentions

Conservatives

Manifesto: 120pp, 28,733 words

Defence: 1,178 words

Health 1,741 words, 72 mentions

Education: 1,184 words, 58 mentions

Afghanistan: 5 mentions

Lib Dems

Manifesto: 110pp, 21,668 words

Defence: 466 words

Health: 1,143 words, 34 mentions

Education: 1,719 words, 87 mentions

Afghanistan: 3 mentions

Greens

Manifesto: 50pp, 20,427 words

Defence: 254 words

Health: 715 words, 59 mentions

Education: 522 words, 35 mentions

Afghanistan: 4 mentions