VIEWERS are used to up-front declarations about a drama’s veracity, yet rarely are they as direct as the one introducing The Sixth Commandment (BBC1, Monday-Tuesday): “This is a true story.” Note that no-nonsense full stop. None of your “inspired by” or “based on” here.

The frankness was necessary because what followed was an astonishing account of the deaths of two elderly neighbours, Peter Farquhar and Ann Moore-Martin, at the hands of a sociopathic conman.

If this had been a work of fiction it would have been criticised as over the top and lacking credibility. I mean, come on, why didn’t anyone see what was going on?

Yet as writer Sarah Phelps rightly judged, this was the banality of evil at work. These were nice people, good people, and that anything dreadful should be happening to them was unimaginable.

The MO was the same in both cases: target the victim, befriend them, move in, and slowly take over their lives, persuading them to change their wills along the way.

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First to be duped by young churchwarden Ben Field (Eanna Hardwicke) was retired school teacher Peter (Timothy Spall). After Peter died, Field moved on to Ann (Anne Reid). Like Peter, she soon fell ill, suffering dizziness and hallucinations.

This was outstanding drama on every front. Phelps set a delicate, mournful tone from the off, which the brilliant Reid and Spall built on as only they can. Best of all, the entire drama - now on iPlayer - allowed the victims their dignity, even in the most difficult scenes. If only all tales of crime, real or otherwise, were as sensitive.

Earth (BBC2, Monday) found presenter Chris Packham in an oddly upbeat mode. Odd because he was standing on various mountaintops, Philomena Cunk-style, warning of the planet’s impending doom.

Think we have it bad with 40-degree temperatures in holiday spots? Let Chris tell you what happened 250 million years ago. Worst mass extinction the planet has ever seen, 90% of all species dead, a fiery hell followed by torrential rain that lasted on and off for almost two million years. It’s being so cheery that keeps him going, you know.

But his main message was that the planet has always renewed itself over time and would do so again. “Extinction is a vital part of evolution,” he assured us. Er, thanks, I think.

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Given the hype beforehand, this five-part biography of the planet was clearly meant to be event viewing, watched on as big a telly as possible. Yet for all the erupting volcanoes it was a visually dull hour. For long spells we were looking at rocks, which was about as exciting as it sounds. Something was missing and it wasn’t David Attenborough.

The film only came to life when Packham, on a boat in the Canary Islands, spied dolphins approaching. “Sorry to be a child,” he shouted with delight. This was more like it. When it comes to celebrating the wonder of the world few can live on landscapes alone.

You did wonder about humankind’s progress while watching Rosie Jones: Am I a R*tard? (Channel 4, Thursday). The comedian, who has cerebral palsy, always wears headphones when she’s out because people shout abuse, including that R-word. When she goes on TV, be it doing stand-up or talking politics on Question Time, a “tsunami” of vile remarks arrives via social media. At one point it got so bad she considered giving up performing.

This hour was part of her fightback. She spoke to others affected by trolling and to tech experts about how it could be controlled. Twitter was asked for a response but did not give one; that alone spoke volumes. She tried to meet with one of her trolls, but none took up the offer so she had to do with AN Other Scumbag. He blamed his behaviour on drink and poor mental health.

He was not what Jones had imagined and by the end of the programme she felt stronger for confronting her fears. She was not going to let the “monsters” win. She was going to call out ableism and urged others to do the same. Whether she succeeds in her aim in making the programme, to make people think twice about ever using the R-word, we can but hope.

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You did not have to be canine crazy to watch Lost Dogs with Clare Balding (Channel 5, Tuesday) but it helped. It is a terrible business to lose a dog, and hanging is too good for the scumbags who steal them, but did the subject merit a live, hour-long programme on prime-time TV?

Like Crimewatch for pooches, Lost Dogs duly gave out practical advice and appealed to anyone who might have seen the lost dogs featured to get in touch. Alas, no cases were solved during the time the programme was on air, but there are two more weeks to go so paws crossed.

Any lingering doubts about the show’s importance vanished on seeing the “reunion videos”. All that wriggling ecstasy and boundless relief, and that was just the humans.