It was a Very light, fired from a Very pistol. The pilot intended to set this part of the field ablaze as well. The stalks caught at once, flames spurting out from the furiously igniting centre of the conflagration. MacConnachie swung about.

‘Back to the break! We’ll operate from there!’

As he emerged again into the corridor, turning his face away from the hissing phosphorus, Ansell looked along the fire-break to his left and saw the leading members of the patrol rounding the bend into view. At the same instant they saw him, and aligned their weapons to fire.

‘Down, Mac!’

He pitched himself violently backwards into the stalks, taking MacConnachie down with him. A burst of rapid fire slapped and tore at the mushy strip in front of them.

MacConnachie was sure the Goons weren’t trying to kill them; they would have been ordered to take them alive. He scrambled up, stepped out into the corridor and fired three carefully aimed shots. Two men went down, the third ran for cover.

The far field was deeply ravaged now, with a tall wall of fire racing towards them; the phosphorus raged blindingly, and the new conflagration set off by the observer was beginning to bite and spread.

‘Come on! We haven’t any choice!’

They ran into the second half of the field. The race against time and fire was on with a vengeance now. But at least the ground favoured them very slightly: the deeper they committed themselves, the more the stalks thinned out – not dangerously, but enough to provide narrow, roughly uniform corridors down which they could run at full tilt.

But there was still the helicopter.

For some moments MacConnachie was puzzled by its behaviour, for, far from pegging them tight, it began to describe a circle too wide to give any but an approximate idea of their position to the pursuers on the ground. Then he saw another glowing fireball shoot down from the aircraft to bury itself in the field to their right, and he understood. The pilot intended to surround them with a ring of fire.

By now they were running flat out, swishing through the stalks as fast as their legs would carry them, the field having become for them both a series of blurred impressions rushing past on either side and instantly snatched away. The blood roared in their ears, drowning all but the most penetrating sounds, as of a sudden outbreak of unexplained shooting to their right.

When he saw the second light fall MacConnachie jinked left, Ansell stumbling after him. The helicopter curled round behind them and, coming up to pass over their left-hand quarter, discharged another flare into the dried-out stalks. This one was closer and as they ran on they heard the flames begin to crackle and bite. MacConnachie continued his bias to the left but the pilot, completing his manoeuvre, flew across their front, and the observer laid his fourth incendiary directly in their path, thirty yards ahead.