When the enemy wants to play dirty

This Sunday, BBC1 screens a drama that is sure to alarm the public and government alike. And so it should, the makers tell James Rampton

At the end of Crimewatch, Nick Ross traditionally tells viewers: "Don't have nightmares." The BBC might think of putting out a similar soothing message at the end of Dirty War. This film, which portrays the cataclysmic effects of a 400kg radiological "dirty" device detonated by suicide bombers outside Liverpool Street station in the City of London, is likely to give you weeks of bad dreams.

At the end of Crimewatch, Nick Ross traditionally tells viewers: "Don't have nightmares." The BBC might think of putting out a similar soothing message at the end of Dirty War. This film, which portrays the cataclysmic effects of a 400kg radiological "dirty" device detonated by suicide bombers outside Liverpool Street station in the City of London, is likely to give you weeks of bad dreams.

I certainly feel a chilly shiver down the spine the day I go down to visit the set of BBC1's new dramatised account of what might happen in the event of such a bomb, containing a teacup full of radioactive caesium 137, being detonated in the heart of London's financial district in the morning rush hour. It's a sunny summer Sunday morning, but, far from being bright and breezy, the atmosphere is decidedly sombre. We are stationed in one of those ultra-modern streets behind Liverpool Street, an imposing canyon of glass and chrome peppered with arty, abstract statues. The area is cordoned off with that police incident tape familiar from countless episodes of Morse and Frost - here, however, it is serving an altogether more weighty drama.

The tape holds back hundreds of extras playing traumatised bomb victims. Coated in ash and wrapped up in bandages, these people are staggering around, dazed and confused, like so many shell-shocked First World War soldiers. While troops in riot gear charge forward to reinforce the cordon and use their shields and batons to beat back angry protesters, police chiefs with bullhorns desperately appeal for calm. They ask people to file in an orderly fashion towards the decontamination units being rapidly assembled by fire fighters in inflated orange Chemical Biological Radiation Nuclear (CBRN) suits. But the officers can do little to quell the air of rising panic. The scene is truly scary because it is all too believable. After September 11, Bali, Istanbul and Madrid, this sort of scenario no longer resides in the realms of pure fiction.

This March, the Metropolitan Police Commissioner Sir John Stevens emphasised as much when he warned that "it would be miraculous if, with all the terrorist resources arranged against us, terrorists did not get through, and given that some are prepared to give their own lives, it would be inconceivable that someone does not get through to London". In the film, before the suicide bombers strike, the deputy assistant commissioner working for SO13, the anti-terrorist branch at New Scotland Yard, echoes these thoughts about the threat from al-Qa'ida: "With the IRA, we knew 90 per cent of what they were up to, and they still got through. With this lot, we're lucky if we know 20 per cent. It's naive to hope it won't happen."

Dirty War is the result of more than two years of meticulous research. It is directed and co-written (with Lizzie Mickery) by Daniel Percival, the film-maker who was previously responsible for the equally disturbing Smallpox 2002, about the rapid spread of a deadly virus. Like that film, Dirty War is a collaboration between the BBC's drama and current affairs departments.

But for all the thorough homework and attention to detail, Dirty War has already been whipping up controversy. It presents unsettlingly graphic shots of a mushroom cloud billowing over the City of London. This explosion causes more than 200 fatalities as well as leaving thousands affected by cancer in the years to come and rendering a two-square-mile area off limits for the next 30 years. It is distinctly upsetting to watch, and even before it has gone out, Dirty War has been criticised by the Government for being alarmist and sensationalist.

It's fair to say that, even though the emergency services in this film perform with heroism beyond the call of duty, the fictional government in Dirty War does not emerge entirely with credit. At one point before the blast, a minister says she is unable to reveal to the fire brigade the full details of her plans for a major emergency. "I'm sure you'll appreciate, we have to limit access to these plans in the interests of national security." To which an enraged watch commander replies: "What a fucking great excuse for incompetence."

In the light of such scenes, Percival is bracing himself for more attacks from the authorities when the film is broadcast on BBC1 this Sunday. The writer-director accepts that "the Government's policy will be to condemn the film as irresponsible. Even last November, the Home Office said it was regrettable." He goes on to stress: "The BBC isn't interested in going to war with the Government, but it has a responsibility to question politicians on matters of public safety. The film is designed to put the consequences of this kind of terror higher on the public agenda and to pose general questions about our level of preparedness."

Paul Woolwich, the executive producer of the film and a man with many years' experience in the field of current affairs, is also steeling himself for an onslaught from the authorities. When I ask him if the Government is happy that the BBC is making Dirty War, he merely raises his eyebrows and casts a knowing smile in my direction. "The Government's policy," he says, "is not to give too much information, because its view is that all terrorist incidents are different. It believes it's as prepared as it can be. However, there is another view: that the British public should be told more, as people in the US and Australia are."

For all that, is there not an argument that this film could needlessly scare people? Not in the eyes of the producers, who contend that, like Smallpox 2002 and, before that, The War Game and Threads, Dirty War is merely providing a public service - a claim substantiated by the major information campaign that will support the broadcast and the heavyweight debate that will follow Sunday's screening.

The film asks such key questions as: are there enough decontamination units in the UK? Do the emergency services have sufficient CBRN protective suits? And do the public know that in the event of a radiological attack, they should stay indoors, turn off air-conditioning units, not touch each other and avoid eating and drinking? Lorraine Heggessey, the BBC1 controller who commissioned the drama, says: "I hope it's not going to panic people. It's there to inform them. All the information in the programme has been accurately researched and is based on the knowledge we had at the time. In some ways, not enough information has been given to the public about how to respond. It's a matter of great national interest. Everybody - from Eliza Manningham-Buller, the head of MI5, and the London Mayor Ken Livingstone, to politicians not just here but in the US and elsewhere - has acknowledged the fact that there is a real threat. The more information that is out there, the better."

Percival argues his corner even more forcefully, asserting that Dirty War is designed as a wake-up call for the emergency planners. He underlines that the film aims to educate viewers beyond the level of the Government's recent booklet covering chemical warfare and bio-terrorist attacks, "Preparing for Emergencies: What You Need to Know".

"I really hope the film helps accelerate the process of preparedness and encourages the emergency planners," he says. "If I could say anything to the Home Secretary, it would be, 'You need to train us far more about what to expect.' The film is not alarmist; it's just trying to be honest. The Government is happy to use the nightmare scenario of terrorists getting hold of weapons of mass destruction as a justification for going to war in Iraq. And yet it is very hard to find real information about what the effect of a dirty bomb would be. If we can look at that coldly and clinically, we can ask ourselves, 'Are we ready?' But that public awareness is where the Government is being most coy - for the arguably good reason that they feel it's much more important to reassure the nation that we're well prepared and secure and to prevent unnecessary alarmism.

"The Government argues that to over-egg the threat could create general insecurity and have the same effect as the boy who cries wolf. But I find that patronising. I'd rather be well-informed and well-prepared and have a civil defence as well-funded as the military. So far, it is estimated that £6bn has been spent on the war in Iraq."

Stephen Barrett, the film's research producer, chips in that he hopes as a result of this film "the Government might invest a little more in its preparations for such an eventuality. They might have set the bar too low. At present, per head of population, the US is spending about 30 times more than us on preparing for a possible terrorist attack. In Seattle and Washington, they held a drill for a dirty bomb that lasted five days. We had four hours at Bank Tube station."

The other criticism of Dirty War is that it may be offering terrorists handy tips about how to mount an attack, but, again, that is an accusation the producers refute. Barrett emphasises "we're not giving away state secrets. We don't want to give bad people good ideas." The BBC sustained a bloody nose in its battle with the Government over its reporting of the run-up to the war in Iraq and the resultant Hutton report. So is it running the risk of picking another fight with the Government? Woolwich says not. He points out that the film was commissioned long before Hutton and says that the report "hasn't made us more nervous. The BBC is still committed to quality journalism in the public interest - and without doubt, this is in the public interest." Dirty War tackles head-on the most critical issue in the world today - the threat of international terrorism. The plethora of programmes on the subject underscores its centrality.

But is there a danger that we'll all soon be suffering from a surfeit of doom and gloom? While acknowledging the risk, Percival nevertheless believes it is vital to grapple with this topic. He says we cannot afford to ignore it. "To put yourself into the mind of a terrorist or someone caught up in something as atrocious as a dirty bomb can be emotionally draining, but I don't get depressed about it. I get angry about things I feel could be better. Perhaps that's what motivates all film-makers - that compulsion to try and do something about these issues.

"It's a real privilege to have an opportunity to address these dark fears and try to contribute to making a difference. Dirty War won't be responsible for radical change in emergency planning, but it may help demonstrate why it's so important to confront these issues." So once the furore surrounding Dirty War dies down, what is Percival planning to do next? "No idea," he smiles. "Maybe a romantic comedy."

'Dirty War' is on BBC1 this Sunday at 9pm