Khartoum in the early Eighties.

I’m not sure exactly when – before they started blowing up aid workers and a few years after Michael Buerk.

We were heading out to Port Sudan – a few scarred concrete hangars on a rubbish tip – and then planning to grind our way south to the Delta by Land Rover, a six-hour journey in itself. We were to pass Harley-Davidsons parked outside Bedouin smugglers’ tents, follow the remains of a Turkish railway through the dunes, and drive around quicksands to an appointment with the Beja nomads.

It wasn’t something I had booked through Thomson: I was out filming with the BBC. This was adventure, eh? And now we were eating in a small, walled garden, and the African night had closed around us. There was distant shouting in the black streets. One of the crew turned slowly to his companion and looked at him thoughtfully. “Is this on expenses?” he asked.

We spent the next three hours discussing the decline of the BBC canteen.

“They change their sky but not their soul who run away across the sea.” Horace, who wrote this, clearly worked for the Roman Broadcasting Corporation.

This Sudan expedition was for Comic Relief. It summed up the duality of “travel experience” at television’s expense. I was a wide-eyed romantic: looking under the bed for black mambas and drinking coffee with the porters late at night, so that I couldn’t sleep in the ruined plantation house full of feral cats. The blokes I was with were leathery BBC foreign-service professionals. For them it was another job: we were going to make a television programme. I was excited. They got a night’s rest.

I love the company of cameramen. But when you go on safari with a film crew, travel is not a personal, introspective, serendipitous, wayward journey. It is an organised coach tour with a ruthless schedule. Or, at least, it ought to be.

You take baggage. You take metaphorical baggage: fulfilling a role, travelling as a group, with an intention and an itinerary. And you take literal baggage, too. There’s a camera and sound equipment and several lenses and batteries and a monitor and spare tapes, some wet-weather clothing, microphones, tape recorders, tripods, filters, a detailed script and a number of people.

Coming back from filming Kipling in India last year, we got to Delhi airport six hours early, but we still had to fight our way through the departure lounge with five laden trolleys. After two hours of apologies, we finally got to the check-in desk.

The man behind us looked as if he were about to cry. The desk girl quailed. I had to walk away and hide. Countless metal boxes were clumped on the weighing machine, taken away to be minutely examined by customs officials, disputed, weighed again, opened, closed, left standing for a bit, checked off against three different lists and finally laboriously labelled and humped on to the conveyor belt, while the queue behind grew ever more incredulous and then openly hostile. For our fellow travellers it was like arriving at Stansted and finding Captain Scott and his ponies in front of you.

Of course, we strive for spontaneity, but everything is planned. The days when a camera crew shot whatever came along went out with Nanook of the North, and were only reintroduced with Big Brother.

It has taken the British press a long time to figure this one out, but I am afraid that all film is essentially “set up”. Meetings have been arranged. Personages have been summoned. Animals have been ordered. A camera has to be started. Sound has to be ready. The crew has booked the hotel. The schedule has to be met. It is a job, not a jaunt.

Later on that first Sudan trip, I stood arguing with a producer about delivering a line to camera on the ruthless West exploiting the impoverished Sudanese by forcing them to grow cotton. This was in front of a field of some sort of herbage, but I suspected the crop was something other than the woolly plant.

“It doesn’t matter. The line has been agreed,” the producer sighed.

“Okay,” I said. But while the camera was being set up, I sidled over to our “fixer”. “Is this crop cotton?” I asked him casually.

He was shocked. “No, sir,” he answered promptly. “I don’t know if you heard about this, but we had a famine here in the Sudan a few years ago, and now we are growing food here instead.”

But, you see, the line had been determined in the office. We were not expected to deviate. People plan films. They have to. Budgets are tight. Executive producers are powerful. In the end, we compromised. “They used to grow cotton here,” I warbled. The producer moved on to other pastures. Her name was Helen Fielding. IF WE are alert, we get some serendipity. In fact, we encourage serendipity. Last year, I went to film the black rhino for Sky. (Why me? Well, apparently the black rhino has the temperament of a slightly crotchety middle-aged man, and I...)

Harry Hook, my crazed and much-loved director, wanted to illustrate the notion of rarity by making a film in which I actually couldn’t find a rhino. We dutifully scoured the whole of Kenya and finally came across one catching a nap under a tree. I was ecstatic – here was my David Attenborough moment. I crept towards it. This was dangerous: if he woke, he might charge at us.

As I turned to whisper, breathlessly, to the camera, I noticed, behind it, the figure of the director, jumping about trying to wake the beast so he could get a shot of the thing rampaging towards us. While I delivered my own health-and-safety lecture to Harry, the rhinoceros got up and slunk away somewhere quieter.

But I am ignoring the elephant (and the rhino) in the drawing room. I am skirting the unbeatable experience of real television. In the 19th century, travellers took a “firman”, a written decree from some nabob, to open doors and get access. Well, the camera is the firman from heaven. Even if it sometimes feels like taking a battalion into a teashop, the camera and all those extra people open doors.

Without television, I would never have sat under a tree discussing water sources with the Masai elders, never have accompanied a field hospital handing out old National Health glasses in a village south of Nairobi, never have stood with night binoculars watching a lion watching me at the water hole in Tsavo. I would not have been allowed to sit in Trotsky’s chair at Trotsky’s desk. It would have been unlikely that I would have been ushered up to the roof of a house in Lahore to watch the minarets light up like Flash Gordon rockets while hundreds of black kites fluttered in the sunset. That firman enabled me to make Kendal Mint Cake in the factory and took me on a wild-pony roundup in Snowdonia. Some coach trip, some itinerary!

WHEN I wanted to write my first travel book, I bought a small boat and sailed to Russia and wrote about a midlife crisis. I managed to explore myself as much as the Gulf of Finland. But over the past year, I have been climbing for the BBC, for a programme called Mountain. Where I had pootled, now I clambered; where I had drifted, now I scaled. The boat got me to Russia, but that firman got me everywhere.

But, even so, there are some things the camera cannot do. In case you’re wondering, the Beeb can’t fake me climbing a mountain – they can’t afford to. And I did ask. There was no helicopter waiting at the top to ferry me out when the director called “wrap”. We often had 2,000ft to descend in the dark before we got to our “luxury hotel”. And, just for the record, I climbed some of those mountains three or four times. If I had been on my own, I doubt that I would have gone back down a hundred feet or so several times just so that the director could get a better shot.

In fact, to be honest, I doubt very much that I would have gone at all. Just getting me out of my armchair was a setup (I am a crotchety middle-aged man, for God’s sake). But I am very glad I did. And I am glad I had my firman, too, because if filming sometimes lacks spontaneity, then it is my job to provide it. And I willingly do that in return for the doors that the magic word, “television”, opens. Not just for me, but, if you think about it, for all of us.

Mountain: Exploring Britain’s High Places is published by Michael Joseph at £20. The television series starts tonight on BBC1 at 9pm

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