“But aren’t you afraid of the dark?” asked the woman in the minibus.

We were climbing from the city of Huancayo into the mountains where I would rejoin the Royal Road. “Afraid of what exactly?” I asked her.

“Oh, you know – ghosts, wild animals, armed robbers, that sort of thing.”

I knew I was unlikely to be troubled by ghosts or wild animals but I was a bit concerned about the armed robbers. I’d already told the minibus at large where I was getting off and where I was going to camp. “Are there armed robbers round here?” I asked.

A man behind us said something in Quechua and the whole bus laughed. I turned to see a smirking, evil-looking campesino, his three-day beard half-hiding a scar across his right cheek. “He says he’s going to come and slit your throat,” said the woman.

This inauspicious start gave me rather a restless night; but no one came to disturb my peace, and next morning I began the descent into the Mantaro Valley, the first of three deep gorges I had to cross before reaching Cusco. The Royal Road eased its way down towards the river, and across the dizzying chasm I could see it climbing again in an endless series of zigzags.

On a narrow riverside ledge the village of Izcuchaca was in full fiesta. The village elders were leading the fray, dancing round the square to the thump, thump, thump of a huge brass band. Percussion and French horns vied enthusiastically, each trying to make the most noise. After a few minutes I was dragged into the circle of heaving humanity and quickly realised that my John Travolta days are over. My knees were still shaking from the descent and I clung desperately to a very old man, a real grandee, in an endless circular shuffle. A bucket of chicha (maize beer) was passed around and as I accepted my third glass I knew the afternoon was going to be a difficult one.

At midday the revellers finally let me leave. The zigzags soared skywards. The heat was stifling, and as I gained height the relief of a tiny cooling breeze was tempered by my gradual realisation that the streams on this side were completely dry. At 4pm, 3,000 feet above the river, I reached a village. “Is there any water here?” I gasped.

“No,” replied a man digging up potatoes. “We get it from the other side of the ridge.”

I followed his directions and two hours further on found a bubbling spring. It was one of the best moments of the whole walk. I put my head down and drank. Then in the rapidly failing light I stumbled through a eucalyptus grove and finally, in almost total darkness, found a small grassy clearing on which to put my tent. Luckily the Vango goes up almost by itself. I banged in the tentpegs, then tumbled inside and was instantly asleep.

A strange distant rumbling formed a background to my dreams, and in the cold first light of dawn I discovered what it was. I crawled out and found myself looking vertically down a full 3,000 feet. The rumbling was the River Mantaro I’d crossed the previous day. I’d set up camp just three feet from a precipice!