Last Night's TV: Mistresses, BBC1Natural World, BBC2

Aha! It's "Joanna Lumley's Mistresses". Actually, that's not quite right. Unlike her previous outing, in which the lovely Lumley was given personal possession of no lesser world wonder than the Nile, this is not, in fact, the official title. But let's not dwell on details: "Joanna Lumley's Mistresses" it was, to all intents and purposes. She came (clad elegantly in eau de Nile suit), she saw (or at least surveyed everything that mattered – in this case her daughter's wandering eyes), and she out-sassed everyone she encountered, trailing the two-seasons-old cast in her formidable wake.

Mistresses is back, but not as we know it. Gone are the little black dresses and tumblers of red wine. In their place, we've got homely numbers straight out of the Toast catalogue and early-morning breakfasts with the children, all set against a kind of charcoal-and-green colourscape. It's part of an effort to make the series more plausible, apparently. Producers, fearing recessionary irrelevance, have capitulated to the critics and sacrificed the show's hitherto bonkers plotlines in favour of something decidedly more sensible. Of course, we've not been left totally without glamour. The cast is so extremely gorgeous, so like something out of a Sunday supplement, that it would be nigh-on impossible to render them ordinary.

Our heroines have fallen out, though it's not clear why. Last night commenced with an oddly frosty meeting, initiated by Katie. "I thought it was going to be just me," muttered Jessica on arriving to find Siobhan present. Judging from the hostile expressions being conspicuously borne, the feeling was mutual. Before we learned too much, we were whisked back six months. Ah, that's more like it: Katie lounging under a palm tree. Except that she wasn't lounging under a palm tree at all, but – a bit of horizontal panning revealed – slumped in front of a malaria- awareness poster in her office. More's the pity! (This, for novices, is the office of the relatively lowly job she maintains, having been booted out of the last position – as a GP – for conducting an affair with a patient.)

Anyway, Katie's mother was in town (in the form of the aforementioned Ms Lumley), so she's got more than enough to worry about. She's also helping out chez Trudi, where loyal fella Richard is running himself ragged looking after the children (welcome to house husbandry, mister). Trudi, meanwhile, was trying to make it as a Professional Domestic Goddess, while Siobhan mooched around pining after the newly engaged Dominic, and Jessica spoke wistfully of marriage. (Yes, marriage! Jessica!) In sum: it was jolly depressing. Forget illicit sex; the most we got was an illicit cigarette – and even that was hastily stamped out when discovered. Which is a shame, really, if you ask me. Mistresses has always offered a kind of heady escapism; these aren't the etiquette-bound Stepfords of Desperate Housewives. They are – well – Mistresses. The clue's in the name. And, much as critics may have deplored the show's outrageous plotlines and characters' lust-fuelled dim-wittedness, I rather liked them. So, I suspect, did the five-odd million who tuned in every week.

It only took 20 minutes of "Echo: an Unforgettable Elephant", the first in a new series of Natural World, for me to begin blubbering into my phone. "She's. Just. So. Wonderful," I snivellingly explained to a bemused friend (this was Tuesday evening, and I was watching my very special Reviewers' DVD, so she couldn't even tune in to sympathise). "She saved all the elephants from famine and she even... adopted... her... grandson... when... her... daughter... died."

It is possible that Echo caught me feeling particularly anthropomorphic, or particularly misanthropic, or, possibly, a bit of both. Still, the fact remains: "Echo: an Unforgettable Elephant" was one of the most moving pieces of natural world documentary-making I have ever witnessed.

Introduced by a suitably sombre David Attenborough, the film followed conservationists at Kenya's Amboseli game reserve as they chronicled the life of Echo and her vast family. Born around the time of the Second World War, Echo had survived poaching attacks, drought and famine to become matriarch of her herd. Along the way, she had engaged in little acts of heroism that speak of a sense of compassion far deeper than standard accounts of animal sentience can explain.

There was the time that Echo's son, Ely, was born unable to walk. Instead of – as might be expected – abandoning him to fend for himself, Echo slowly coaxed the screaming calf off his knees and on to his feet. Within days, Ely had stopped crying out in agony and shuffling around on the floor and was starting to toddle around properly. And there was the time that Echo's daughter, Erin, died after being speared for her tusks. In her absence, Echo tracked down the spot where she died to be confronted with her carcass. Massaging the bones mournfully, she appeared fully aware of their owner. She adopted Erin's son and led him and the rest of the herd to Tanzania in search of vegetation not devastated by the drought.

When Echo died in May last year, it wasn't just her human keepers who mourned. Her herd lingered round her bones in the same way she had lingered around Erin's. Shortly after her death, the calf that she taught to walk returned a strong, trunk-swaying bull. It was incredibly poignant, watching him touch tusks with his relatives but being unable to find his mother and, without doubt, as stirring as any human drama.