Television: Lonely desert crossings, and other imperial pursuits

The television explorer is an anachronism, a case of the 20th century in pursuit of the 19th. His quarry - and it usually is his rather than hers - is not so much an undiscovered country, because no such thing exists any more, but a time when there was such a thing. This must be why survivors of the posher end of the English public school system are so adapted to exploration in the media age. Boarding school has trained them to live in the past and in the most wretched conditions.

The BBC's latest man on a mangy quadruped is Benedict Allen. I don't know where he went to school, but a fiver says he went to School - as Etonians refer to their alma mater among themselves. (As in, "You went to School, didn't you?") There are certain subtle tribal markings, and Allen has the full house - the round, confident vowels and the nonchalantly brimmed hat, the blond amiability and the loosely-tied tongue, the dilettantism which is less can-do than might-as-well.

Allen was last spotted sloping across the Namibian desert on a camel in The Skeleton Coast. For his next trick, he is pony-trekking through the Gobi desert in Edge of Blue Heaven. Why? Why not? The official motivation for Allen's journey is a yen "to experience modern Mongolia as it emerges from obscurity" - to see the place before the rest of it, like Ulan Bator, is colonised by Pierre Cardin and the Spice Girls. Given that the country is the size of Western Europe with fewer people than Wales, he may have exaggerated the imminence of westernisation. But whatever, from this distance Allen's reason for going looks like window dressing. The BBC doesn't as a rule dish out videocams to people pretending they're from National Geographic. The videocam is the solipsist's Swiss Army knife, an indispensable tool for prising open cans of worms, and with it Allen's unspoken brief was to explore the explorer.

There's one snag with this, though. The explorer from School may spend his life putting a girdle round the earth, but one place he won't have passed a lot of time is the snow-swept wilderness of his own interior. That way, danger lies. When Allen was invited along to watch some splendid golden eagles hunting a fox, they failed to make a kill and he was, he said, "not too upset about that". A lucky escape for all concerned, because Allen would rather not have to show emotion. You could see that when he took a preparatory stroll before mounting his untrusty steed for what he called "the great off". "It's very important for me to calm down before the start of an expedition," he explained. (He doesn't look the type to be anything but calm, but we'll let that pass.) "That sounds a bit..." And then he saw the No Entry sign slung across his own navel, and trailed off.

The irony of Allen's stated aim to observe Mongolia as it emerges from obscurity is that it is precisely series like this that are ushering it out of obscurity. The most surreal episode in the first of the programmes, on BBC2, came when a man arrived by motorbike at the encampment on the eve of Allen's departure. (The natives, unlike the explorers, have heard of the internal-combustion engine.) From a box on the back of the bike he produced a mobile cinema, in the form of a TV and VHS. In a kind of anthropological short circuit, the only films he screens to indigenous communities are foreign documentaries about themselves. As Allen digested this information, it must have come home to him just how well trodden his itinerary already is.

"There's no such thing as the back of beyond any more," he mused ruefully, no doubt calculating that a copy of Edge of Blue Heaven will soon find its way into this nomadic branch of Blockbusters. When the subjects of his film see his portrait of their life, they will all laugh at the memory of palming him off with a psychotic pony. And so in the coming weeks will we. Nothing goes round the globe as smoothly as a good joke, not even an explorer running from his own reflections.

Wilderness Walks is more up-front about the connection between landscape and mindscape. Cameron McNeish conducts hearty interviews with public figures in the course of a knackering hike. There's nothing like a breath of fresh air to breathe fresh air into a conventional format. This week, he accompanied Donnie Munro, who used to be the lead singer of Runrig and stood for Labour in the 1997 election, round the Red Cuillin of Skye. From Big Ben to big bheinn.

Munro would never normally blag half an hour on prime time to disseminate his views on land management in the Highlands and Islands, but the quite magnificent photography helped you up the steeper inclines of the interview. In fact the camera does all the hard work, because the only thing anyone ever has to say about the hills is itself as old as the hills: that they remind you how insignificant you are. "It brings you back to a sense of proportion," said Munro. There's a kind of inverse vanity in using landscape as a way of looking at ourselves through the wrong end of a pair of binoculars, but in a rock star you'll accept any form of humility.

And there's nothing like a good walk for downsizing your vocabulary. Munro and McNeish chose the superlatives on a strict rota system; "Fantastic" followed "brilliant". McNeish hit on a novel wheeze for boosting his stock of descriptive words: he is enlisting them from other syntactical areas. "Wilderness," he theorised hopefully, "is almost more of an adjective than a noun." In which case, Wilderness Walks is goodness entertainment.