The railway’s end at Nam Tok is not dramatic. Its final buffers are set in an earthen bank, above which stands a decrepit and melancholy small shrine. Beyond the shrine, up a side path, a heavy teak pavilion faces a modest waterfall. Another one hundred yards beyond the pavilion is a teak guest house sometimes used by the Thai royal family, and where our guide said that Princess Alexandra had once stayed. A few yards beyond the guest house and you are in jungle. Look back in the direction you’ve just come from and perhaps you can detect where the high embankment and two small connecting bridges must have run, but farther to the northwest – nothing but undergrowth and trees. I found some old sleepers and a couple of old iron pegs on an embankment.

I had originally wanted to go as far north as Takanun, near the Three Pagodas Pass on the Burma border. Inoh had been my camp commander there during the horrors of that 1943 monsoon, which had ended in epidemics of cholera and cerebral malaria. But we were told that nothing remained of any of these camps; the place was solid jungle.

Instead, I viewed the immensity of our joint achievement from the vantage point of a U.S. Army helicopter. Craggy, rugged hills and mountains all the way, covered with forest. Occasional long plains, also jungle-covered, where presumably the line must have run rather than go over the mountains.

But nothing of our work was visible from the air – nothing whatever.

‘Just goddam jungle,’ said our pilot, sighing.

To be accurate, this is a monsoon rain forest – huge thick trees, teak, bamboo thickets, but no matter overhead, no ‘impenetrable’ secondary growths. Good tiger country.

But the whole time I was in Thailand I never even heard a tiger’s roar or a panther’s cough. The only dangerous snakes I saw were a few cobras. Our deadly enemies were minute by comparison – the anopheles and tiger mosquitoes which brought malaria and dengue fevers, and the ordinary flies which spread dysentery and cholera. These were the scourges of our lives. Our furthest northern point was to the farm of an extraordinary Thai-Chinese I had met, named Yup. He said he had benefited from our railway in that he farmed about four thousand acres of virgin land in the area of a former camp called Kinsayok. He seemed to have definite views on the value of our efforts as labourers, so we decided to pay him a visit.