One afternoon, father, son and I sat beneath a spreading acacia and divided up our duties for the trip. In other words, Suleyman announced that he would look after camels and navigation, Samir decreed that he would cook and look after the water supplies, and then, rather worryingly, with both of them nodding vigorously, Suleyman explained I would be in charge of everything else.

In a land without borders it was clear we needed some of our own. If we were heading off alone together, we needed rules.

I had no qualms with the first one that they suggested: one should not, under any circumstances, pour milk on the sand, because the earth was impure and it would undermine baraka. And number 2, another Tuareg custom, seemed just as harmless. When washing a bowl, the water must be poured on a stone rather than the ground.

Number 3 was undoubtedly in all our interests. Imujagh, dignity, was to be guarded at all times. Boasting, coveting and jealousy resulted in illness and an attack of bad spirits. Words can reach the soul and be equivalent to killing a person, just as compliments can provoke jealousy and desire.

Nor did I object to number 7: that all female camels travelling with us had to be milked daily, otherwise evil entered the milk and it would have to be boiled.

It was all going so well. Number 8 relating to physical modesty received nods all around. This included ankles and forearms, because in the desert showing those parts of the body is tantamount to flashing. To this effect, we would be taking no almonds or peanuts, since they were high-risk foods bound to light a man’s fire.

And Suleyman was perfectly welcome to the job of trimming the camel toenails, checking their urine colour and monitoring their hormone levels. And that a camel should never, ever eat the leaves of the difl, or oleander, seemed entirely logical, considering that it was poisonous.

In return, I requested a few of my own ‘guidelines’.

Number 1 was agreed suspiciously quickly: separate tents. Whatever the terrain or weather conditions, however exhausted we were, there would be two – one for the men and one for me – pitched at a respectable distance from each other. I was British. I had standards.

But the no-alcohol rule proved predictably divisive. I insisted on having a hip flask. Samir protested that it would lead to immodest thoughts and, Allah knows, the mind was the weakness in men and the root of evil. And so we added a caveat, reserving the right to drink alcohol ‘in emergencies’.

There were restrictions about rations, supplies and, of course, water. Two cups a day as a ration for ‘hygiene’, apart from drinking water, seemed unbearable. I was used to two showers a day.

The avoidance of religion and politics as conversation topics was hastily agreed by all parties. No matter what any of us thought of East–West relations, the ongoing occupation of Syria and Palestine, we would respect our differences.

Subsequently, Samir and I added a few of our own small points. Telling a girl how nicely she smelt in relation to camels was a slippery slope. Telling a girl how bad she smelt after a day’s trek was just rude, even if it was true. Yet strangely, telling a man he smelt bad after a day’s trek was a compliment.

And the deal breaker:

I was never, however near to death from dehydration, going to drink my own pee.

Samir looked at me and as I glanced back at him I felt as unknowable and alien to him as the great seas of water across the Atlantic where he hoped to swim one day.

The camels had their own set of rules, of course, although they alone were privy to what they were.