It's 6am. The sky is the colour of gruel as the mist clears, and there is the fine scent of old wood smoke in the cold air. From deep inside my thin sleeping bag I can hear nothing but a cacophony of pigs, chickens, dogs and buffaloes grunting, crowing, barking and snorting. Beside me is the rhythmic chanting of a Buddhist prayer as my 75-year-old host kneels on the bare teak boards of his house in the mountains of northern Thailand and prays to a small photocopied image of a Buddhist prayer wheel pinned to the wall.
It takes me a while to remember where I am and, indeed, why on earth I came. This has been the most uncomfortable night of my life. Nine hours earlier, after an incredible yellow curry, cooked over an open fire in the timber building by our guide Singh, we had stretched out on the cold wooden floor and tried to sleep. We had been driven into our sleeping bags by the cold, the noise of the animals and the darkness around us. Only once we'd lain down did I realise just how torturous the next nine hours would be: cold, noisy and painfully uncomfortable.
I'd come because in 1943 my grandfather was posted to Burma, where he was stationed at Imphal at the time of the Japanese siege. Here, he and his comrades were billeted under canvas - uncomfortable during the torrential rains of the monsoon. He made contact with some of the local Karen tribespeople and learned from them how to build a bamboo hut, into which he moved for the remainder of his time there.
Since that gruelling siege, surrounded by the Japanese, under air bombardment, and working 24-hour shifts to man important but technologically fledgling radar equipment, he had talked with fondness of his meetings with these hill tribes and so I had always wanted to visit them.
Today, many of the tribes are persecuted or driven into forced labour by the Burmese authorities, and have escaped over the border into Thailand, where they now live in a scattering of shabby villages in the mountains west of Chiang Mai. In many ways, my host and the rest of the inhabitants of this small village in the bucolic Mae Wang Valley are the lucky ones. An hour and a half's drive from the refined and rather attractive regional capital, they live in a beautiful, secluded valley where life is hard, but moves at a sedate pace. Further west are the refugee camps into which Karen and other hill-tribe people continue to flow - according to Amnesty International's annual report, there were almost 143,000 Karen and Karenni refugees in camps along the Thai-Myanmar border last year.
The evening we arrived, our host family had been sitting around on the bare boards of their home as the sun set. Before I visited, my guide had asked me to sign a form absolving him and his company of any responsibility, should I smoke opium with the villagers. It's a problem among the older tribespeople and, with the help of backpackers and other visitors, one that is spreading to the younger generations.
Rather disappointingly, the older tribe members were not smoking opium, but instead chewing a grim mixture of tobacco leaf, betel-nut and limestone powder made from a rare local rock, which, I was told, is burned and then dropped in water before being ground to dust. Their blackened teeth and gums give away these betel chewers. Occasionally they would shuffle to the edge of the homestead and hawk up great wads of the concoction on to the earth.
The old couple's son and his new wife were preparing for a night out at a nearby village, where there would be Thai boxing, drinking and maybe a dance. She crouched by the edge of the platform cleaning her teeth over a small enamel bowl; he sat with us swigging from a bottle of locally made rice whisky - sweet and powerful. Around us were the sounds of village life, unchanged for centuries: animals and children, punctured only occasionally by the more modern noise of a motorbike or truck. The village has been here for about 150 years. In that time little appears to have changed. The large timber-framed houses built on stilts are dotted about the slopes of a hill overlooking a fertile valley of rice fields. There is a road of sorts that winds up a steep hill, but in the village itself there are only pig runs of compacted mud between the houses.
In the space beneath the houses buffaloes and pigs sleep and scavenge, barefoot children play in the dust, and the women of the village gather to hang out the beautiful woven cotton scarves, throws and shawls that they spend their days weaving. And they are adept at weaving. We bought some scarves, each of which had taken roughly three days to make by hand, but cost us just 150 bhat, or about £2. To say these people are poor would be an understatement.
Elsewhere in the village there was a single, frankly squalid latrine block, to which we had to stumble in the dark, and a small shop where the entire stock was lined up neatly along one small shelf. Three cans of Singha beer stayed cool in an ancient, rusty refrigerator. The shop was run by girls - no more than 15 years old, each dressed in a striped dress of red, orange, green and blue cotton, denoting her status as a married woman, and each with a child on her hip.
Last month, General Saw Bo Mya, the revered Karen resistance leader, died in Burma. He had led the Karen National Liberation Army, which he helped found, until 2000. The KNLA is fighting for independence from Burma and for the creation of a separate state. It is a fight that began back in 1949, after my grandfather and the rest of the British army had returned home. The Japanese invasion had thrown into sharp relief the tensions between the hill tribes - of whom the Karen are the largest group - and the Bamar majority in Burma. Since then, the Karen have marked 31 January as Karen Revolutionary Day: the day their fight for autonomy began. This year will be no different.
In the almost 60 years since my grandfather made contact with the tribe, the region has changed dramatically. The people, however, still cling to their traditions. As the last notes of the Buddhist chant faded into the chorus of waking animals, I stretched out, glad to be up as the village came to life; glad that the night was over. But also glad that I had finally come.