As I lay shivering — despite my thermals — in the sleeping bag, with my water bottle frozen solid outside the tent, cream slapped on the sorest parts of my body and listening to the wind as it whipped through the campsite blowing away the makeshift lavatories, I asked myself, not for the first time, why I had ever agreed to ride a horse from the Pacific coast of Chile to the Atlantic coast of Argentina in the first place.

The idea was daunting even before we started but by the time the journey was over — after 600 miles (1,000km) and three weeks of wind, dirt, cold, campfire food, bad backs and saddle sores — it had taken on epic proportions.

Three quarters of the way through I decided that there were two groups of people on this trip. The first were the “nutters”, who loved riding, loved the horses and loved the experience, and if they had the chance would willingly turn round when they reached the Atlantic and go back. I decided that Chris, the mate I’d come with, was a nutter.

And then there were the “quitters”, who at the worst moments of adversity simply prayed that a helicopter would arrive and whip them off to a hotel, with a hot bath, comfortable bed and civilisation. I was definitely a quitter.

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That none of the quitters actually quit was partly to do with not having the opportunity to escape: on the whole journey we came across only three or four remote towns; and usually we arrived 15 deep on horseback, as if we were straight out of a spaghetti western. Transport links to these towns were rudimentary and in Telsen, the last of them, we arrived late on a Sunday afternoon to discover that the first bus out was on Wednesday.

But of course by the time we got to Telsen it didn’t matter because we were then two weeks into the challenge and, with only five days to go, what did matter was to finish, to reach the Atlantic irrespective of the pain. Even Jo, a 42-year-old mother of four from Kent, who had never slept in a sleeping bag before, let alone camped, didn’t really want out — and she’d had a bad back since the early days in Chile.

For me there was a special reason why the experience was odd. I got married the week before we left for the trip and it was a pretty strange way of spending a honeymoon, especially because my wife, Sue, declined to join us — thank God. As the trip got harder I spent one night working out the list of the people I knew who would have hated the trip the most. Sue was at the top.

I should point out that the three-week adventure across Patagonia was booked long before the wedding was arranged and that our marriage was unusual in that we had been together for 27 years and brought up four children before we decided that it was time to tie the knot. But even I would have to accept that taking my mate Chris on my honeymoon was unusual and there were a lot of Brokeback Mountain jokes.

Chris and I had ridden long distances before — two years ago for a week in South Africa and last year for six days in Argentina — but we had done nothing on this scale for this long. It was in Argentina last year that we met Jane Williams, an Englishwoman who runs an estancia (ranch) there. When she e-mailed to say that she was organising a coast-to-coast ride, Chris persuaded me to go.

On day one we walked our horses into the Pacific in a Chilean fjord south of Puerto Montt and set off on the epic trip. There were 11 paying guests — Americans, a German, one guy from Zimbabwe and seven Brits, with more women than men. Remarkably, I was the youngest of the male guests, not something that happens often when you are 61. The oldest was 72.

Crossing the Andes on a horse was pretty special, if hazardous. The scenery was stunning but on day two we nearly lost Chris when, on a mountain pass, a swarm of wasps made his horse panic and the two of them went over the side, taking with them the horse and rider in front of them.

Chris found himself 40ft down, flat out by a lake with his horse hanging on a tree above him. That night I had a nightmare in which I had the job of telling Chris’s wife, Kath, that he was a goner. I woke up half the campsite shouting in my sleep.

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