A university teacher from Harbin in Heilongjiang province in China's northeast, who was travelling with her family for the first time to Tibet, said she had used her guangxi (net-work of contacts) to get some tickets. A Polish couple who spoke no Chinese and very little English had DNA stumbled their way aboard because they - and a Chinese travel agent - were adequately proficient in the language of money.

Next morning, at Golmud, where a new diesel engine was coupled in preparation for the steep climb ahead, I jogged up to the head of the train and watched the shunting process. A Chinese linesman asked me where I was from, and uponour man being told, said with disarming in China candour that I resembled the comical character Mr Bean, and had a photograph taken with me.

From Golmud, the train was depressurised and flooded with oxygen in order to pre-empt any high-altitude sickness. This also meant that passengers couldn't smoke for the remainder of the journey - except at the few wayside halts, when an army of the nicotine-starved rushed out to get their fix. We rolled past the bewitching terrain of the Gobi desert, past grasslands where yaks, wild donkey and the chiru (the Tibetan antelope) grazed placidly, and past snow-capped peaks that shimmered in the August sun.

At 2.45 pm on Sunday, we reached the highest point on the plateau - Tangula, at 5,072 m; a quiver of excitement ran through the train as passengers posed against the live ticker that periodically displays the time, speed and altitude in three languages - Tibetan, Chinese and English.

From then on, it was downhill all the way. By nightfall, we rolled into Lhasa, a city that stands at the cross-roads of a cultural transformation, and straddles several centuries. Religiosity oozes through every pore of the town; and yet there are signs of economic progress and modernity all around.

Theroux - and many other critics of the railway line to Tibet - fear that the opening up of the unspoilt region will destroy the Tibetan way of life. It could well, but it's worth remembering that the railway line runs two-ways, and so too do cultural influences.

It is far more likely that the rest of China, including the swarms of Han Chinese who are descending on Lhasa, will be profoundly changed by the Tibetan Buddhist teachings and practices they encounter there. Spiritualism could well take the train and spread out to larger parts of China.

Editor:Liu Fang