Last Night's TV: A Very Dangerous Doctor/Channel 4<br />The Shadow Line/BBC2

In 2009, the BBC broadcast a Panorama special, A Very Dangerous Doctor, about Dr David Southall, the controversial paediatrician repeatedly struck off by the General Medical Council. And now, here's Channel 4 with its very own version. The name's the same: A Very Dangerous Doctor. The star's the same: Dr Southall – older, plumper, more wild-eyed than last time – but the allegations against him are different. Different, not new.

While the previous programme looked at Southall's role in the cases of Sally Clark and Mandy Morris – in both instances, he alleged that a parent was likely to be involved in the death of their children – this one focused on his treatment of other couples, most of whom had come to his attention after deliberately seeking out his help for their children's breathing difficulties. Southall won renown as an expert in the field. He also, using highly controversial methods including undercover surveillance, became the face of a new kind of diagnosis: Munchausen syndrome by proxy, where mothers invent their children's ailments, inducing the symptoms with ill-treatment. One of the principal motives of those with MSBP is attention seeking. In many cases, the fact that these women desired Southall's expertise was deployed as evidence against them.

But first things first. There's no doubt that Southall's early work – or some of it – encompassed serious accomplishments. He suspected certain parents of creating their children's ailments through suffocation and poisoning. The secretly collected videos showed that, in some cases, he was right. Evidence came in the form of grainy, disturbing footage of ghostly figures smothering ghostly bundles in the night.

He must, therefore, have saved some lives. But he also destroyed others, or so say the women interviewed here. All of them were on the receiving end of an MSBP diagnosis, and all have paid a price. There was Janet Alexander, accused of poisoning her son Lawrence, and Janet Davis, who Southall said was aggravating her son's allergies. But it was Dee and Dave McLean who appeared the most extreme case: when Southall accused them of poisoning and smothering their third son, Ben, the boy was taken into care for a year. He was also, according to paperwork released by the hospital, enrolled in various tests conducted by the doctor. It was these tests – which saw children deprived of oxygen for short periods of time – that the McLeans hold responsible for the brain damage Ben has experienced.

Alarmingly, Southall doesn't seem to hold parental consent in the highest regard. Asked about submitting infants to testing without written consent, he insists it was standard procedure. Likewise the occlusion testing he was using, halting the children's breathing for 10 seconds at a time. Not everyone agrees. Dr Paul Johnson, a long-term sparring partner of Southall's, was adamant that the measures were extreme: "You can trigger an event by doing that."

Amid all the toing and froing, it's impossible to know what to think, but easy to feel sympathy for the children. Certainly, the mothers' case wasn't helped by the presence of Penny Mellor, who's campaigned on their behalf for years. Which would be fine, of course, were she a rather more convincing person herself. With a conviction of conspiracy to abduct a child under her belt, and a habit of chain-smoking on camera, she didn't inspire the greatest trust.

At the heart of the matter were competing questions of motives. Why would these mothers continue to pursue him if they were guilty? Why would such an eminent – or previously eminent – doctor risk his livelihood if not to protect the children? And why the repeated appeals if he wasn't confident of his innocence? They're impossible to answer, though the narrator seemed, in tone at least, to side with the parents. His encounters with Southall became progressively more combative as the 80 minutes wore on. It's not clear – and I wish it had been more expressly asked – whether Southall still believes all of the women (even those like Davis, whose case was dismissed by the authorities) were guilty of harming their children, or whether he concedes that he might, occasionally, have got it wrong. All that was overshadowed by the looming charge of grievous bodily harm the women themselves were pursuing on behalf of the children subjected to Southall's testing. As we left things, the Crown Prosecution Service had decided not to pursue the charge further, believing a conviction impossible. Still, so many questions remained.

Last night's The Shadow Line was exciting for all sorts of reasons. Chiefly, because my block of flats had its very own cameo. It didn't, I should add, show the neighbourhood in the best possible light. Our roof flashed up midway through a crime chase, which began in my local park and ended at my local Tube.

But it was also exciting because – unlike last week – I could actually understand it. All the way through, not just at the end. We had a bit of a head start, of course, what with having met all the characters themselves. Still, it was a novel feeling. Much of the action surrounded the various attempts to track Andy down. The driver of the car in which week one's gangland drug lord was shot, he's been MIA ever since the accident. The result was a frantic chase through Bethnal Green, which, as I can testify, is actually a Very Nice Place indeed (for a car chase).

a.jarvis@independent.co.uk; twitter.com/aliceazania