Monty Don, Monty Don, Monty, Monty, Monty, Don, Don, Don. What a mellifluous moniker – and it comes with one of those clever internal half-rhyme things I can’t remember the name for. But I can always remember Monty Don’s name. You can hum it under your breath to the tune of One Man Went to Mow. I’m told there are people who whisper it as a green incantation to bless seedlings: “Monty be with you.” I expect, when his agent first phoned a commissioning editor and said, “I’ve got this man called Monty Don you should see”, the Tristram just yelped: “I don’t need to see him, book him.” It’s the perfect telly name: proletarian, but with a touch of bookish wisdom. It isn’t just a combination of two first names, but a meld of the matey shortening of two first names. And all that’s before you even get to look at him.

What a specimen of early-evening presenter. Monty is the reincarnation of Hardy’s Gabriel Oak (if fictional characters can be reincarnated). Whereas Alan Titch-marsh, for all his rambling, is still the evocation of suburban patios, Monty is redolent of a wilder, more ancient throb. He has an ancient boskiness, a Celtic spirit – the green man. He comes from a preindustrial land of peasantry, a place of half-remembered folk song and Catweazle. I’m awestruck by his wild, set-aside, organic beauty, that perfect unkempt meadow of hair, the charmingly lopsided five-bar mouth and all the Bodenish foliage of corduroy and faded cotton, the solid daisy roots and manly man bag. He is retro, eco, postmodern: a difficult look to pull off, but Monty does so with gusto. He is the mulchy, double-dug fantasy of a great many of the female audience, who dream of being espaliered up against a warm garden wall.

His new big series, Around the World in 80 Gardens (Sunday, BBC2), started last week. It’s not much of a title, really. Getting around anywhere in 80 anythings implies a wobbly, unfocused concept that’s been dumped into an off-the-shelf formula. But the first programme opened with a dewy promise. We began in Mexico, with the floating market garden that the Aztecs built, which became Mexico City after the Spanish drained the lake they were on, looking for gold. It wasn’t the Aztecs who had the gold, it was the Incas. Then we saw a modern architectural garden that was plantless, a concrete surrealist garden built in the jungle and a cactus garden, then went on to Cuba for the starving people’s garden.

It was an inspiring, if chaotic, start, not least because none of this is what most of Monty’s fans would consider a garden at all. So we waited, bated, for Monty to explain it all, to make its wonder live, to drench our parched cerebellums with insight and knowledge. He smiled his crooked smile, shrugged his pergola shoulders and opened his mouth – and what came out was the sound of the wind in the trees, a scarecrow creaking in a field of sunflowers. He made the cardinal mistake of presenting and told us what we could already see. He then made the second mistake of presenting by paraphrasing what we would be thinking if we were standing where he was. Extraordinary, he said. He said it many times. Many things were extraordinary. Extraordinary things, in particular, were extraordinarily extraordinary. Having gone to all the trouble of getting to frankly extraordinary places, Monty had forgotten to pack a script or even a few jotted notes, trusting instead to his enthusiasm, alfresco impressions and faded cotton. It was left to an editor to try to topiary some rough logic from his rambling. It was a terrible, terminal mistake. There was so much we yearned to know – so many questions hung in the air – but what we got instead of intellect was “amazing”, “astonishing” and “extraordinary”.

I gather the weedy message was that we should learn things about stuff and be green and local and colloquial, which all seems a bit thick coming from a bloke who’s just dragged a film crew round the world, wasting carbon faster than he wastes exclamations. Monty is a lily of the field, he neither reaps nor does he sow, which is a bit of a drawback for a gardening presenter. Mind you, he’d look good in a vase.

Wonderland (Wednesday, BBC2) is a documentary strand that began a fortnight ago with The Man Who Eats Badgers, a brilliantly observed, idiosyncratic look at strange and lonely men who live on Dartmoor doing dysfunctional, strange and lonely things, occasionally to badgers. It was a story that couldn’t have been told in any other medium: nothing else comes close to being this good at describing or revealing intimate personal experience or the telling details of unexamined lives. This week, Wonderland targeted virtual adultery, about avatar affairs on the web’s sad, ugly, gimpy Second Life. This was less compelling than the badgers. The online world was not so much a cause for infidelity as a symptom of unhappiness. The film-makers were trying to make a narrative their subject didn’t prove. We were given flaccid confirmation that online sex is a great deal less erotic or fun than sex using Balinese shadow puppets. People who indulge in it aren’t so much broadening their sensual lives as avoiding having one altogether.

Just as I was beginning to think the standalone personal-view documentary was going to be made extinct by the creeping freakery and phoney suspense of reality shows posing as information, this week produced a good handful of old-time, well-made factual films about strange and compelling subjects. Storyville offered Jonestown(Sunday, BBC2), about the mass suicide of the communard religious community in Guyana in the 1970s, the folk who did so much for the marketing of Kool-Aid. The original audiotape of the killing, which started with the children, and the accounts of the survivors, all of whom had lost entire families, was harrowing but strangely disengaged. Few of us can empathise with extremist religious paranoia; we can’t imagine how you get to the point of queuing up to kill yourself. But what might have been just a ghoulish news story a few years ago looked horribly current, if not prophetic, today.

There was also a sad film, The Found Children of Argentina(Tuesday, More4), on the use of DNA to find the children of “the disappeared” by their grandmothers; and Timewatch presented a memoir of the Ten Pound Poms (Saturday, BBC2), the English who emigrated on assisted passages to Australia in the 1950s and 1960s. They wanted to get away from worn-out, class-ridden Britain and to have a sunny life not doing much of anything. Their stories were touching triumphs and small, sad failures. It is easy to be moved by our refugees in their struggle to make a life abroad. Funny how we manage to be so intolerant about other people who try to do it here.

Factual television is still how most of us get most of our information and form our opinions and prejudices. It can be the most succinct, intimate and humane of mediums. Everybody understands the telly, and every day it offers a vast amount of easily assimilated information, much of it trivial and forgettable, but some of it abiding and occasionally profound. So, it was a good week for knowing stuff – almost the full Monty.

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