Last Night's TV - The Secret Millionaire, Channel 4; Two Pints of Lager and a Packet of Crisps, BBC3

There's nothing very secret about the success of The Secret Millionaire, the sixth series of which began last night. All the features of feel-good drama are there. The hero in search of redemption; the epic quest for meaning; the deception of noble souls for their own, ultimate benefit; and the final reconciliation, in which a grand "reveal" brings all parties to the same dais of knowledge. Why on earth didn't they think of that earlier?

That the show is embarking on another series is testimony to its enduring appeal. By the time each episode finishes, we ache with the glorious sense that a better world is possible, that good may triumph. This feeling alone justifies our hour-long investment, as it did last night, when Sean Gallagher was dispatched to Middlesbrough with customary zeal. And even for a show as formulaic as this, his fitness for the role was exemplary.

For 12 years, he told us, he had built up an IT recruitment business (is there a drearier three-word phrase in English?) as a kind of surrogate for his personal failings. A long relationship with a fiancée broke down, and he never found love again. This deprived him of children, so instead he directed his paternal sensibilities toward his two nieces, a project made poignant by the death 25 years ago of their mother – Sean's sister – through an epileptic fit. That event was the true beginning of our plot, so that the chronology was disrupted and constantly informed by painful memories of an event we never saw.

Even before he got to Middlesbrough, the waterworks had begun. Sean didn't often speak about his sister. The presence of a camera and crew cajoled him into confronting his anguish, but each time he did so it proved too much, and he stepped away to compose himself. These teary recollections combined with an over-zealous script, so that by the time we got to the first ad break the sense was that Channel 4 was laying it on a bit thick. Our hero boasted of his £8,000 LED television, on which he just loved to watch sport; we saw him looking out over the balcony of his lush penthouse in Spain; then he was testing out a £120,000 Aston Martin, telling his man at the dealership he just loves that new car smell.

Cut to Sean traipsing around grim Middlesbrough, interviewing locals about their quotidian miseries. Then the script went into overdrive, piling cliché on to cliché. This town allegedly has the country's highest levels of unemployment – compared with other towns of similar size? Among what age group? And was that trusty thing, a Northern "former economic powerhouse", "blighted by drugs and crime". Such phrases don't take much imagination, but Sean reinforced the message with the highly predictable assertion that this place was "like a war zone". There followed shots of him peering out from behind his curtains, and close-ups of his home security.

All this was in aid of pumping up the contrast between where he had come from and where he was now, but this was draining long before the missionary had done his work. He was more than redeemed, however, by his efforts for charity.

Sean turned up at the offices of Fairbridge, an extraordinary group that helps children who have fallen between institutions. It would be remiss not to mention that Fairbridge does precisely the same kind of work as Prospex, a charity in Islington of which I am a trustee, because I could see a familiar dilemma on the face of the workers and their young people. Many young people who might be involved in crime are terrified of the camera, fearing a conspiracy from the police. For Sean and his Channel 4 team to have convinced them to take part was a considerable achievement in itself. And Fairbridge's staff were also in a familiar difficulty, of not wanting to seem desperate for exposure but keen for all the help they can get.

Our hero had the most wonderful rapport with the young people, refusing to patronise them and sensitive to their intelligence. It was thrilling to watch; but even that was not as heart-wrenching as his second charitable encounter, with the founders of Abbie's Love. This small charity was set up by the parents of a young girl called Abbie Clarke, who died of an epileptic seizure. The link to Sean's sister was immediate, and didn't need to be laboured. Abbie's father lived with the guilt of thinking his daughter was asleep when in fact she was in a seizure. All he and his partner wanted was to raise money for bedside alarms that would prevent future such tragedies. The solidarity between our grieving brother-hero, and these grieving parent-champions, was marvellous television.

I dare say it left me exhausted, though. By the time we got to the opening salvo of series nine of Two Pints of Lager and a Packet of Crisps, the old compassion fatigue was setting in. And devotees of this show, which used to be awful and is now rather addictive, will know that Gaz (played by Will Mellor) is now in a wheelchair.

Just as in Byker Grove many years ago, when PJ and Duncan, later and less enjoyably known as Ant and Dec, went from being joyful youngsters to morbid goons after the paintball accident that blinded PJ, so sitcoms are harder to pull off when the main character is paralysed. Laughter feels wrong. Send for a secret millionaire, I kept thinking to myself, and undo this injustice.