The patrol started from Zella oasis, the new headquarters of LRDG, about two hundred miles south of the coast road where the armies fought and where – thank God – the insects stayed. They kept just over the horizon from the next oasis at Hon, where the Italians were supposed still to have a thousand soldiers in residence, and near the end of the first day came out onto the flat gravel of the Hamada el Homra, the Red Desert.

It was a small group, just ten men spread among two jeeps and two much-converted thirty-hundredweight Chevrolet trucks. They were looking for a unit, or advance guard or patrol – call it what you like because it could be pure rumour – of French colonial troops coming up from somewhere in West Africa.

From the beginning of the war, there had been over 120, 000 French soldiers in Africa – regular, colonial, native and Foreign Legion – vaguely loyal to Vichy but mostly just counting their fingers. A few, Ledere and de Carette himself among them, had come up to join 8th Army long before. Now, after the Allies had landed in Morocco and Algeria and the Germans had torn down and thrown away the Vichy government like old Christmas decorations, there was a rush from the other French garrisons to get back into the war.

They appeared almost anywhere. They raided and even captured Italian outposts, they ambushed convoys and sometimes each other – but the one thing they never did was tell anybody else what they were doing.

"If a French officer came to me," a choleric colonel in Benghazi had said, "and told me where he'd been, what he'd done, and where he was going next, I'd have him shot as a German spy. He'd be no bloody Frenchie!"

De Carette had begun to wind himself up into a cold fury, but then remembered that he was very young and junior, and that this colonel was his door into the romantic behind-the-lines warfare of LRDG, so shouldn't be slammed carelessly. And anyway, he knew there was enough truth in the comment to agree politely. Very coldly, but politely.

That was their only task: to find the rumoured French unit. Contact with the enemy was to be avoided. On the other hand, it was a big desert and the enemy might not know contact with him was to be avoided, so they carried the more-or-less standard armament of twin Vickers K guns fired from the right-hand seat of the jeeps, with a single Lewis and a belt-fed Vickers machine-gun in the Chevs. They also had rifles, pistols, Tommy-guns, grenades, land-mines, 808-type plastic explosive and a few incendiary candles. Just standard equipment.

The patrol seemed to be one big family, perhaps more than a family, since the ones who didn't fit had been thrown out. They came from any unit in the desert and wore any bits of uniform they happened to have – most of it all at once, in the January chill, topped oif with a greatcoat or goatskin jacket. Nobody wore the flowing keffiyah head-dress any more: it looked splendidly romantic, but it also caught in the steering-wheel or the chattering bolt-knob of a machine-gun. A knitted woolly 'comforter' didn't.

Nobody seemed to use ranks or even real names. Tyler was 'Skipper' and only de Carette was 'sir' – the newcomer, the outsider. He wasn't sure he really wanted to be part of the family, but he did want to be asked.

"They were very fair," de Carette recalled. "They saw I could drive perhaps better than any of them, so they let me have one of the jeeps. John drove the other. You are too young, both of you, to remember, but before the war most French and English soldiers could not drive at all. Except a few who had been drivers of trucks for a job, and the boys of parents with some money. My family had some money, and I had driven a car in Africa since I was big enough to see over the steering-wheel. I expect it was illegal even then, but…"

An hour before sunset they stopped for the night. Just stopped, because on the flat plain there was nowhere to hide. The Signals sergeant from the wireless Chev erected his flimsy aerial and started tapping out a position report. Others unloaded just as much as they needed for the night and no more, because they might need a fast getaway. They serviced the vehicles, cleaned the guns and everybody filled his water bottle. Nobody went anywhere without a full water bottle.

They had done 150 miles, not bad considering the basalt rocks above Hon and it being a first day when newly-stowed stores could shake loose and even fall off. But Captain Tyler was strict about things like that, preaching gently that a tin of meat and veg wasn't important in itself, only when you couldn't find it. At twenty-seven he was older than any of them except the Signals sergeant.

One of them cooked a stew of tinned M and V over the traditional 8th Army stove: one of the old flimsy petrol tins bodged with holes and half-filled with petrol-soaked sand. It burned surprisingly tamely for a surprising time. The tea came thick and horribly sweet, made with condensed milk. De Carette made no comment.

At the moment of sunset, the Red Desert suddenly lived up to its name. The rusty plain turned to blood in the horizontal light, then richened through all the scarlets and purples of raw meat as shadows stretched out from inch-high pebbles. Only the colours moved; everything else was quite still. Everybody stopped and watched; none of them had been this far west before. They lit cigarettes and the smoke drifted almost straight upwards. Then the colours faded and darkened to colourlessness, and the patrol gave appreciative grunts and went back to their jobs.

"Always something new," Tyler said, his long face becoming an opera devil in the red light. "Ex Africa semper aliquid novi. We may impress ourselves with what we're up to, but I doubt we'd impress old Pliny. Although it was some Greek who said it first…"

He rambled on in his slow, serious voice, and de Carette flattered himself that Tyler might be glad to have a companion to whom he could quote Latin. Yet the scholar and soldier seemed to blend without a seam showing, and Tyler wasn't condescending when he argued with Corporal Bede about the unnecessary complication of the Tommy-gun. Was this some Anglo-Saxon duplicity?

But he was right about the desert: always something new. To some it was a mysterious woman, to others an old bitch who never knew her own mind. Neither pretended to know the 'desert'. It would change subtly, from gravel to tiny stones to bigger ones and then sharp rocks that carved at your tyres until your arms were limp with winding the steering-wheel and your speed had dropped at least ten mph (or ten mih – miles in the hour – as the Army put it, just to remind you this wasn't a Saturday afternoon picnic). And then the lady might throw a real change of mood at you, like a crumbled escarpment that fell away a full three hundred feet that you wouldn't have chanced even in one of the new Sherman tanks.

Or perhaps a miniature mountain range, jagged as broken glass, poking out of the plain like the backbone of some vast dinosaur. All quite unexpected, of course.

The desert was a very old lady. And there were almost no maps of her face.

Tyler poured everybody a mug of rum, lime-juice powder and water, then one by one they wrapped themselves in sleeping bags under tarpaulins stretched from the vehicles like tent-halves.

The night turned viciously cold under a sky crowded with stars that shone, not twinkled, in the diamond-clear air. They were all young, fit and well rested, so nobody felt very tired yet. There wasn't much talking, but matches flared and cigarettes glowed until well after midnight.

Around noon on the third day they slid down the western escarpment off the Hamada and, according to dead reckoning navigation, crossed into Tunisia.

Unexpectedly – as you'd expect – the desert changed to short, sandy-grey hummocks wearing toupees of crackly brush that broke off and jammed in the track rods and exhausts. It had a depressing and unnatural nastiness, like the man-made deserts of rubbish and broken cars beside the railway yards outside big cities. It slowed them anyway, but they also went more cautiously.