The driver of the micro-bus crossed himself several times in the Catholic fashion as we crossed a mountain pass, around 4400 metres up in the Andes. Behind us was La Paz, and the steep rocks on either side of the road gave way to a magnificent valley below. The road dived down into steep kinks, and I hoped the driver would have more than his faith in God to get us down.

Several hours of breathtaking views later, we stood in the village of Coripata, at the heart of Los Yungas, a major coca producing region on the eastern slopes of the Andes. "All these hills are coca," explained Angel, the owner of one of the plantations. He said that most of his crop is for chewing, exported to Argentina, Chile, Peru, and only a small proportion goes to make the maté de coca, a sort of green tea made from stewing dried coca leaves, that we have been drinking religiously since arriving in Bolivia.

 "We learned that much of the village who had seen us walking around thought us to be the new  padres"

"We learned that much of the village who had seen us walking around thought us to be the new padres"

The village is stretched along ridges, elongated and curving with the contours of the mountains. Our first night here was spent supping Paceña, the Bolivian beer, in the village square, trying to explain to a local drunk that we are English and Italian, not German nor Argentinian, respectively, despite his best attempts to convince us otherwise. The following morning, we learned that much of the village who had seen us walking around thought us to be the new padres—or priests—and were very happy that we were "so young".

As the sun rose steadily higher, out in the fields many of the villagers slowly brought themselves to their feet from shade under trees or lean-to structures. Their bags emptied of dried coca leaves (chewing the leaves is a stimulant, and "can help you walk all day under the sun"), they began to pluck leaves from the small, stout bushes. The bushes can be harvested three or four times a year (depending how high they are), and we arrived towards the end of one of the harvests.

Brandon, a quiet little nine year-old, was out in the fields. He gets 4 bolivianos for every pound of leaves he picks, and can pick up to about ten pounds in a day. Four bolivianos is just under 60 cents, so on a good day he can earn about $6 (just under £4). He doesn't like the work "because of the mosquitos", and says his back hurts at the end of the day.

Driving back to La Paz along the North Yungas road, a dirt track that takes perhaps three hours to navigate, vast swathes of untouched forest clings to the steep mountainside, and waterfalls cascade from heights that my eyes could not reach. Back on the tarmac of the main road back to La Paz, posters extoll the virtues of the recently re-elected president, Evo Morales, proclaiming him to have brought back dignity to coca. But before reaching La Paz, one must pass through a roofed checkpoint, with a sign declaring Control antinarcóticos. How much of this local stimulant ends up not as green leaves stewing in tea, or chewed in mouths, but as white powder snorted up noses?

Many of these (iPhone) images have already appeared on my Instagram feed, @philmoorephoto