Dillon moved in. 'Bombs aren't just bombs, they are tactical weapons, used to achieve maximum results. You must make sure that an ambush is not just an ambush, but a total disaster for the enemy. And to achieve that, you need instruction from an expert.'

'What are you saying?'

'Let me tell you a story,' Ferguson said. 'It's from thirty years ago, when I was a Major in the Grenadier Guards, on my third tour in Ulster, seconded to staff at headquarters in Belfast. I'm not wasting your time, believe me.'

'Then proceed, General,' the President told him, and Ferguson began.

'August the twenty-seventh, Nineteen seventy-nine.' Ferguson took a deep breath, as if pulling himself together. 'I'll never forget that date because it was one of the worst days in my life. I was in the Incident Room at the Grand Central in Belfast when we received some truly dreadful news.'

'Which was?' the President enquired.

'The Queen's cousin, Lord Louis Mountbatten, liked to enjoy his family holidays in Ireland, despite the obvious security risks. That year, a radio-controlled bomb blew his thirty-foot fishing boat apart, killing Mountbatten, his grandson, his daughter's mother-in-law and a young boat boy.'

'Dear God,' the President said. 'I remember reading about it.'

'God had nothing to do with it, but the Provisional IRA did. The media went berserk. At the Incident Room, we were besieged, calls from all over the world. Then later that same day, just when I thought it was beginning to calm down, it got worse. Warrenpoint. Two trucks loaded with paratroopers were on their way to a market town called Newry when a huge roadside bomb hidden in a farm trailer was activated by a radio signal. Six paratroopers were killed and others wounded. The survivors took refuge in the ruins of a lodge at a place called Narrow Water. They radioed in for help and came under sniper fire. A Wessex helicopter carrying soldiers from the Queen's Own Highlanders landed close by. As they disembarked, another large bomb exploded, killing twelve soldiers, including their commanding officer and wounding others.'

The President's horror was plain. 'That's appalling.'

'I use it in my lectures at Sandhurst as an example of a classic guerrilla ambush brilliantly executed,' Miller told him.

Ferguson said, 'It was probably the worst incident in terms of casualties in the whole of the Troubles. Eighteen men dead and more than twenty wounded.'

'So where are you going with this?' the President asked.

Miller took a map from his briefcase and unfolded it. 'Afghanistan, Helmand province. See the road running up to the mountains in the north, the small village of Mirbat and the deep lake beside it? The village is in ruins, the people have moved on. A convoy loaded with technicians and electronic equipment needed to get through to the dam at the head of the valley to repair the hydroelectric system that the Taliban had damaged. Two six-wheel Mastiff armoured patrol vehicles led the way. Besides the drivers, there were twelve Rangers. When they got to Mirbat they found it deserted, got out to explore, and a massive roadside bomb killed six of them instantly and wounded others.'

The President said, 'What next?'

'The remaining Rangers came under sniper fire from across the lake. A Chinook helicopter with an instant response medical team happened to be close by, Brits as a matter of fact. They reached Mirbat in fifteen minutes and landed. As the medics jumped out, a second roadside bomb was activated and the helicopter fireballed.' Miller shrugged. 'The firing stopped, the Taliban cleared off. In all, there were twenty personnel involved. The entire Chinook team were slaughtered, and ten Rangers. Two Rangers survived, along with the driver.'

'Sixteen dead,' the President said grimly.

Ferguson said, 'Shocking, isn't it? Even more so to listen to.'

'Listen to? You mean, this is one of the things your Major Roper picked up? With the British voices?'

'Yes. Voices calling to each other in the fog of battle, the death of men, the triumph of the victor,' Ferguson told him. 'The Taliban force could have been as many as thirty. The experts estimate about fifteen were British.' He removed a cassette from his pocket.

The President took it and said, 'Clancy, would you put this on? We might as well hear the worst.'

The material had been enhanced and edited. Some of the voices were speaking Pushtu and there was an occasional call in Arabic, but English prevailed and the different regional accents were clear. For a while, there was a lot of crosstalk, and then someone cut in with real authority.

'Shamrock here. Cut all this stupid chatter and assume your positions. Mastiffs are on the way. The soldiers in them are American Rangers. They're good, so wait for the bomb to explode before firing. Anyone who jumps the gun gets a bullet through the kneecap from me afterwards.'

There was a certain amount of wild laughter, and then an American voice cut in. 'Calling convoy. Ranger One. Coming into Mirbat now. Looks pretty quiet to me, but we'll see.'

Shortly afterwards, the first explosion was followed by gunfire, voices calling excitedly, screams, the sound of AK47s firing. Then a sudden silence.

Miller said, 'Major Roper's cut straight to the Chinook arriving.'

The pause ended; there was the noise of the Chinook coming in and then the second explosion, deafening in its intensity, followed by further gunfire and then the voice again, loud and clear.

'Shamrock here. Cease firing. You've done well, you bastards. What a spectacular. Warrenpoint all over again and it worked big time. Osama will be delighted. Now let's get out of here before the heavy brigade arrives. You can rest in peace now, Sean. Night bless.'

There was suddenly only the machine whirring. Clancy said, 'Is that it?'

'It sure as hell was enough,' the President said, his face sombre. 'Why haven't I heard of this before, Blake?'

'It only happened nine days ago, Mr President. You were in Mexico for two days, then that courtesy call in Panama, and then the Libyan business.'

'That's what I'm elected for. This is bad.'

'Yes, but Major General Ferguson thought you should hear this personally. This has been the first opportunity.'

'You're right, of course.' The President took a deep breath. 'We're grateful to you, General. Now this leader of the pack, this Shamrock. What do you know about him?'

Ferguson said, 'Our voice experts say he's educated, likely the product of a top public school.'

'And a trained soldier?'

'I'd say so,' Ferguson said.

'Which means the British Army,' Dillon said, 'and he has Irish roots of some sort.'

'How can you be certain?' the President asked.

'The code name he's chosen, Shamrock. What could be more Irish than that? Then there was his joy over the success of the Mirbat ambush, and his comparing it to the Warrenpoint spectacular of so many years ago. Also, his threat to shoot anyone who misbehaved through the kneecap-that's a ritual punishment in the IRA since time immemorial. Finally, this rest-in-peace prayer to someone called Sean.'

'Surely that's a common enough name in Ireland?'

'It certainly is,' Dillon smiled. 'A good Irish name which in Northern Ireland would label you as a Catholic instantly.'

'I'll have to take your word for it, Mr Dillon. Most enlightening.' The President stood up. 'Gentlemen, I'm very grateful, and you've given me a lot to think about. General, I know the White House has owed you and your people a debt on many previous occasions. Keep Blake informed of your progress and let me know if there is anything I can do.'

'We're grateful for you finding a moment to see us,' Ferguson told him. 'We live in trying times, but we'll pull through, I'm sure of it.'