But these are not hairdos at all; the girls have metal platters on their heads — platters brimming over with fist-sized spiders. Their dreadlocks are not dreadlocks, they are hairy legs.

The spiders are dead. They smell so pungent because they’ve been soaked in soy and deep fried. And now I’m expected to eat them.

I am in Skuon, home of the world’s most repellent roadside snack: a thing even less palatable than the 3am doner kebab. I hand over 500 riel for an incy-wincy portion — one arachnid — and finger it uncertainly, wondering if it would be rude to put it in my sunglasses case and take it home to scare the milkman. The legs are the size and colour of a Cadbury’s chocolate finger, though if your chocolate finger was as hirsute as this, you’d definitely take it back to Sainsbury’s.

Just then another car pulls up and a German named Ulli jumps out. Ulli is not pussyfooting about. He buys a dozen spiders, hands his girlfriend the camera and takes a great big bite. It’s even worse than I feared: brown gunk explodes down his chin, and he’s spitting and choking. Tra, my safari guide, turns away and winces.

“Never eat the abdomen,” he whispers. “Eggs or excrement.”

Skuon is the first staging post on my sally into undiscovered Cambodia, and a taste of things to come. Until a decade ago, the phrase “undiscovered Cambodia” was travel tautology — but then Pol Pot died, the Khmer Rouge was finally vanquished, and the world, its wife and a busload of in-laws flocked here to visit Angkor, lost capital of the god-kings, the most humdinging archeological site in Asia. Now, a million tourists pitch up each year, including Korean coach parties wielding megaphones.

Angkor must be seen, certainly — but if you wonder what the 1,000-year-old civilisation of the Khmers looked like before it got “discovered” by French colonists and tarted up for the megaphone masses, you need to strike out beyond Siem Reap into Cambodia’s steaming, spidery highlands. Here lie the outposts of Khmer empire: Sambor Prei Kuk, a religious complex even older than Angkor; Koh Ker, jungle stronghold of the usurper king Jayavarman IV; and especially Preah Vihear, a cathedral-sized monastery chipped into the top of a 2,000ft crag. A new “temple safari” promises to take travellers with intrepid urges to find them — and that’s what I’ve signed up for: just me and my tent (and my driver, my tour guide, my cook and my factotum).

The brains behind the safari is Nick Ray, Lonely Planet author and self-styled temple-hunter, whose love affair with Cambodia has gone from collecting bottle-tops for Kampuchea to unearthing Angkorian citadels for Angelina Jolie to romp through in her Lara Croft hot pants.

“People think the places you’ll be going to are just for the hardcore dirt-bike community and Mick Jagger in his helicopter,” Nick tells me. “It’s not an easy ride, but once you arrive, you get to spend dusk and dawn alone in your own personal temple — no hawkers or hassle, and a feeling of spiritual communion that’s hard to find nowadays at Angkor. It’s a blast. That’s what I love about Cambodia: it’s still as much an adventure as a holiday.”

Spider savouries are only the start of it. The big worry with back-country Cambodia is not coming home with too many legs but too few. During decades of murderous civil war, the northern hinterland was sown with 4m landmines, and the road to Preah Vihear is staked out with grinning skull and crossbones — which mean step off the trail and you’ll end up like Long John Silver.

We bid goodbye to 21st-century Cambodia in Kompong Thom, a one-horse, two-horsepower town full of kamikaze mopeds loaded with chickens and children. The high street is like a life-or-death Dodgem rink, and I see one chap with a full-grown pig strapped sideways across the pillion of his scooter — which is funny, but not as funny as when I realise the pig is alive.

Soon we’re out in the country and space-hopping north along vivid red-sand roads through the rice paddies and sugar palms, where babies and buffalo bathe together in the levees. Mopeds dwindle away to ox carts, pick-up trucks to ploughshares, and Tra points out a woman baking fish inside a mud oven by the road: “This is the way of cooking that’s depicted in the bas-reliefs at the Bayon temple in Angkor,” he says. “Life hasn’t changed for 900 years.”

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