The pilot nodded and pressed on.

Six hundred metres out, one of the men on the deck lifted his AK47 and started shooting.

It was nothing more than a gesture – an AK is useless at that range – but it made the pilot think again.

He slowed the helicopter to fifty knots, so that it was simply keeping pace with the yacht.

‘Go on!’ shouted the sniper on the left hand side. ‘They can’t hit us from here. I need to get closer.’

Again, the pilot nodded and tilted the helicopter forwards.

Both snipers were now leaning well out of the aircraft, trying to get their sights on the centre mass of their targets.

The left-hand marksman shook his head in frustration and hauled himself back inside.

‘This is no good,’ he shouted, to his colleague. ‘I can’t maintain the target in the scope. I’m going to try with the 41.’

He stowed his AMP, unclipped his Heckler & Koch G41 assault rifle, and leaned back out.

Way outside the effective range of the weapon, but he could at least keep the iron sights on the group and maintain better situational awareness.

‘Closer!’ he said.

In response, the pilot dipped the chopper slightly, to gain on the terrorists.

At which point, one of them vanished inside the boat.

‘One of them just went below,’ said the co-pilot.

‘Seen,’ said the pilot.

‘Keep going!’ shouted the left-hand sniper.

What happened next happened very quickly.

The Lucky Lady suddenly slowed, meaning that the helicopter shot forwards relative to the boat.

Both snipers temporarily lost her, as the controlling pilot throttled back, lifting the nose to avoid getting within 7.62mm range.

At the same moment, the terrorist who had gone below now reappeared, carrying something long and black in his right hand.

In one smooth motion, he hefted it onto his shoulder, braced his feet, and looked up.

‘Oh, shit,’ said the pilot, instinctively breaking right, away from the contact.

Unfortunately, the manoeuvre simply made the roaring engine – and its heat signature – more visible to the missile’s infra-red sensors.

Below him, out of the pilot’s eyeline, there was a flash, and the Russian-made 9K38 Igla MANPAD released its projectile.

The pilot had pushed the Eurocopter hard right and down, desperately trying to throw the SAM off, but, with no countermeasure capability on the aircraft, they were dead and he knew it.

The missile detonated a little over a second after being fired, igniting the 280 litres of avgas still in the tanks and turning the front of the aircraft into an inferno.

As the disintegrating helicopter started to spin and descend, the snipers could hear the pilots screaming over their headsets.

The left-hand man unbuckled himself and leaped out, breaking his legs and back when he hit the water two hundred feet below, and knocking himself out.

He drowned shortly afterwards.

The other three men lived only until the aircraft itself smacked into the surface and exploded.

By which time, the Lucky Lady was already back up to top speed, and powering south through the choppy Mediterranean Sea.