Sniffing for Victory

The plastic explosive C4 is the American-made equivalent of the British and European PE4 (which stands for "plastic explosive 4"). It's a harmless-looking off-white colour. But its effects are deadly. "Eight ounces of plastic explosive would blow a car to smithereens. An 8oz stick would be the size of a candle, about 1.25in in diameter and about 8in long. Under a car it would blow your legs off and blow the car to pieces.

"In an aircraft, depending on where it was positioned, it could take the aeroplane out of the sky. Even a piece the size of your thumb in the cabin area would cause decompression and all the problems associated with that. And if correctly placed, it would definitely bring an aircraft down. To put it mildly," says Major Chris Ham, "you don't need much."

We're standing on a muddy hillside in Leicestershire, in front of a table impeccably laid with a white tablecloth, as if for some surreal, hellish tea party. The table setting features neatly arranged lumps of lethal explosive: TNT, Cordtex, C4, Semtex, and machine guns, sawn-off shotguns, pipe bombs, car bombs (the latter fitted with one of the terrorists' favourite timers: a switch from the trusty Parkray electric fire).

This is the Defence Animal Centre, where the Ministry of Defence trains its MWAs – "military working animals". Search dogs – popularly known as sniffer dogs – are now taking an increasingly important role in preventing terrorist attacks, after 11 September, and after Richard Reid's bungling attempts to blow up American Airlines Flight 63 from Paris to Miami with C4 explosive packed inside his trainers.

"After 11 September we were asked to see if we could train dogs to identify someone carrying explosives," says Ham, Commanding Officer of the centre's Canine Division. "The problem, which we identified immediately, is that if a suicide bomber walks into an establishment and a search dog starts to get all excited and jumps up and down, the bomber knows he's been identified – so he presses the button, and it's all over.

"So we want a dog that will not really show any reaction, but whose handler will know when it has detected something. The handler, because of his experience, can pick up things from the dog, long before the dog really reacts. So we're thinking about the drill; one possibility is for the dog to go straight and stop its front legs moving. But that's just our initial thought as to how we can counteract this [threat]. But I see no reason why a dog could not be trained, as with a drugs search dog, to find explosives on a person."

The centre's spokesman, Major Peter Downing, says he cannot reveal the source of this request, but it clearly came from some senior government or security agency level. "Because the MoD is a government body, we were requested to check on the feasibility of it," he says. "So it's under study at the moment."

Ham says the use of explosives search dogs is greater than ever, and is set to rise. "The demand for search dogs and protection dogs will definitely go up. We're seeing signs of that already. And I know that the Americans took a lot of dogs from Britain over to the US for training for this type of work." It seems, he says, that they prefer the British-bred springer spaniels, Labradors and Border collies, which are best suited to search duties.

After four to six months' training, these dogs can variously locate hidden arms, explosives, drugs, dead bodies, mines, currency, ivory – or people (such as illegal immigrants). Among the centre's clients, alongside the armed forces, are Customs and Excise – for whom it trains drug detection dogs – and the UK Immigration Service. It also trains dogs for the prison service, the police and overseas governments.

The dogs can be "multi-role" – or trained to detect more than one substance. "In our work in Kenya, we found that around a cache of ivory, you may also find concealed arms and ammunition," says Major Downing. "We then trained those dogs to work on arms detection, as well as ivory. It's a scent pattern that they are trained to detect, and it's not restricted to one. As long as there is a scent, essentially a dog will trace it, within reason. A tiny grain of explosive, for example – one would expect that the dog would find it.

"The dogs' sense of smell is phenomenal compared to ours. Dogs are not infallible – they could have an off-day, the same as any of us. Nobody can guarantee it – but if you want to find something, they are going to be the best means of doing so, without doubt."

A senior government scientist says that a dog's sense of smell is "probably about a million times better than a human's. They're living in a world of scent, and their brains work very differently to ours in that respect. Their social life, their food gathering and all of those things are based around scent. They sniff it out, rather than look for it. Whereas humans live in a world of light and vision, dogs are olfactory-based; they live in a completely different world to us."

Chris Ham says the popular belief that smothering contraband in mustard or pepper will throw dogs off the trail is largely erroneous.

"The scent of the target they're trained to detect will still come out; so normally that will not work," he says. "When we're on escape-and-evasion exercises – where you're training soldiers to evade the enemy – the guy that wants to run away may cover himself in horse muck or cow muck, because he thinks that will cover him up and he won't smell like a human being. But to the dog, he just smells like a human being covered in cow muck.

"So it's very difficult to cover up a scent – I've seen guys get a 9mm round, tape it all up in plastic, and throw it in a hedge. The dog will find that even more easily, because it's a bigger 'scent picture'. In most cases, the more people try to conceal things, the easier they make it for the dog. If you were putting a weapon in a hedge for a terrorist to use later, you'd put it in a plastic bag so that it wouldn't rust or get dirty. But that plastic bag round it just makes more scent, and makes it even easier for the dog to find."

The Defence Animal Centre turns out some 300 fully trained dogs a year (most are donated by members of the public). Out on the muddy hillside beyond the neat rows of kennels, there's a swathe of waste ground that looks as if it might once have been under the stewardship of Steptoe and son: a row of abandoned cars, a defunct phone box, a mildewed old caravan, a derelict railway carriage, a couple of empty houses, a dumped freight container, and a big mound of rubble. But these eyesores have all been carefully placed here for a purpose. This is the training ground, where the dogs are taught to search for bombs, drugs, bodies or guns.

One of the officers puts a thumb-sized lump of PE4 plastic explosive in a biscuit tin, and hides it under a paving slab at the door of one of the houses (these, too, were specially built). Scally, a Border collie, is unleashed by Lance Corporal Kelly Kramer. After briefly running around, the dog sits down quietly, right by the slab. It only took a couple of minutes to find. Then Kramer throws the dog a ball – its reward.

"The dog's taught not to touch the substance," says Staff Sergeant Paul Bunker. "It's a conditioning process whereby the dog learns to associate the scent of the substance with being given a reward – which in this case is a ball to play with. It knows that if it finds the substance and sits or lies down, it will get its toy. We don't give food as a reward. Play is a better motivation than food – the same as it is for a human. If you like doing something as a game, you'll probably enjoy it more than you would a bowl of sprouts."

Scally's reaction to finding the explosive – lying down and looking at it – reflects the new style of training "passive response" search dogs. Formerly, the "proactive" training would make dogs bite and scratch at their target. "If the dog scratched at a bomb it could mess up evidence, but worse still, it may set the bomb off," says Ham. "This has happened, and it has destroyed evidence, and has killed people. So we brought in the passive-response dog." Customs and Excise have recently introduced these dogs – which they call "sit-and-stare" dogs – to search yachts, vehicles, baggage, freight and people for drugs, currency and smuggled consignments of cigarettes at UK ports and airports.

"The main problem, at an airport for example, is that with hundreds of people around, what you don't want is an enthusiastic dog leaping up at people," says Major Downing. "You just want a simple indication from the dog, because an innocent person doesn't want anything to do with it. So passive response is the most acceptable method for the public."

Neither the Anti-Terrorist Branch, nor Heathrow, nor Gatwick, nor BAA, nor the Department for Transport Local Government and the Regions – which sets standards for airport security in Britain – will discuss the role of explosives search dogs at airports, for security reasons. ("All information can be useful to someone," said one spokesman. The DTLR would only add: "We don't discuss levels of security, but it's fair to say that it's certainly been increased since 11 September.")

BAA, meanwhile, has allocated an extra £10m to its UK airport security budget for this year. Its X-ray baggage-screening machines also incorporate "trace-detection technology", which can identify traces of explosives, with back-up from a hand-held device, which can be used as a further check. But Chris Ham reckons that nothing can beat a dog.

"Arms and explosives search dogs must have saved hundreds of lives in theatres of war, and in terrorist attacks," he says. "They've either found the device before it goes off and kills people, or locatedthe weapon that's hidden away to shoot somebody at a later stage, and deprived the terrorist of that weapon.

"We've found tons of explosives in Northern Ireland, and tons of weapons; and hundreds of weapons in the Balkans – all with dogs. A search dog can find any type of explosive. Technology, as good as it is, is not as good as a dog. It'll be a long time before technology beats a dog's nose."