He cries, he forages, but redemption may still elude cast away Phillip Schofield | Martha Gill

Idea for a TV show. Cancelled celebrities compete against each other for the ultimate prize: public forgiveness. Hosted by a coterie of bitchy medieval priests, contestants run through a series of challenges: prayer, pilgrimage, fasting, prostrations, public flogging, tearful confessions, sackcloth and ashes, a spell in the stocks and walking naked through the streets to cries of "shame, shame". Points to be allocated by the public according to how authentically humiliated and remorseful each contestant seems to be. The stakes couldn't be higher. Redemption awaits – and only one sinner can triumph.

Not only would it be a ratings hit, banished celebrities would be falling over themselves to take part. We know this because recently they have taken to requesting their own baroque public punishments in the hope that they can worm their way back into public life. But, unlike the penalties once dished out by the church, it rarely works.

Scholars of medieval penitential practice may have got a jolt last week on the release of Channel 5's new trailer for Cast Away , which features a strained and tearful Phillip Schofield alone on a long stretch of sand. He cries, he walks alone, he confesses to his mistakes, he forages for food, he despairs at his fall. "I know what I did was unwise. But is it enough to completely destroy someone?" he asks the camera. (Oh dear, not quite penitent enough. Points deducted.)

"It's a metaphor, isn't it? He is going into purgatory. He is going to suffer," showbiz crisis PR Mark Borkowski told the Times.

Last year Schofield quit This Morning after he confessed to an affair with a much younger but not underage colleague – an abuse of power that resulted in public disgrace . But suffering purifies, and perhaps redeems.

Schofield is not the only out-of-favour public figure who has identified reality TV as a suitable public square for a redemptive flogging.

Another is Matt Hancock , whose first attempt at redemption was on I'm a Celebrity... Get Me Out of Here!, where he was forced by other contestants to admit that there was "no excuse" for his behaviour. No forgiveness followed though – perhaps his ride was too easy – so he then tried Celebrity SAS, where he was tied up in the rain with a bag over his head and called a "weasel-faced cunt" by hard-man interrogators . It still didn't work.

What is a humble penitent to do? Back in 1174, in order to earn forgiveness for the murder of Thomas Becket by his knights, Henry II merely had to walk barefoot through the muddy streets of Canterbury and suffer 300 lashings at the hands of monks. Job done.

Even more helpfully, some medieval clerics possessed handbooks on how to assign appropriate punishments for particular moral crimes – although bishops sometimes cautioned against publicising the "less familiar" sins. By contrast, today we seem to have a blanket sentence for every moral misstep, no matter how large or small: banishment.

Modern life offers no formal path back for the cancelled – a conundrum that seems to have celebs hankering for the days when they could quite literally crawl their way back into public favour. What to do with those not sinful enough to be absorbed by the justice system but not moral enough to be welcomed back into the community? At present, they are caught in a kind of limbo: with no fixed sentence to serve, no prescribed acts of public service to work their way through. It's a sort of nightmare scenario, in which to appeal for forgiveness or attempt to defend yourself is merely to attract more negative attention.

Who cares? Why not let them rot for ever? Am I trying to defend Schofield and his ilk?

I'm often surprised by the reaction to those who have fallen out of public favour. Not just to big sinners such as Schofield, whose self-confessed "unwise but not illegal" actions were, yes, certainly bad, certainly in violation of any sensible HR policy – but even those on the minor end of the sin scale.

A sort of primitive pre-justice instinct seems to take over when we think about those of whom everyone else disapproves: the breaking of any moral rule deserves the strongest possible punishment, and those who dare to defend them must be taken down too. Looking at our instincts it's a minor miracle we managed to come up with a workable justice system in the first place.

A more enlightened society might do something different with this group of sinners – those who have shown themselves to be immoral but not quite criminal, and want to earn back our acceptance. Our current way of dealing with them can seem rather arbitrary. The harshest judgments do not always fall on the worst offenders, as the powerful and the shameless can often shrug off public disapproval – plenty of big sinners are back early, while smaller ones still languish in exile. And it is attitudes, as much as crimes themselves, that often rub us up the wrong way.

It's telling, for example, that the Newsnight interview that ended Prince Andrew's role in public life – last week immortalised for the second time in an all-star TV series , A Very Royal Scandal – did not reveal anything new about his involvement with Jeffrey Epstein and the financier's network of underage women. Or indeed whether he'd had a relationship with Virginia Giuffre, the Epstein victim who accused him of having sex with her. Instead it revealed his arrogance, his idiocy, his unquestioned misogyny, his cosseted lack of self-awareness. It was this that the public could not stand.

Perhaps, after all, television is not the arena in which the cancelled should seek redemption. But there is a modern example for public figures who want to earn back respect, and it doesn't involve eating badger gizzards on live TV. After the revelation of his affair with Christine Keeler, John Profumo worked unpaid at Toynbee Hall in east London – a course of dedicated public service that eventually earned him great admiration. Could cancelled celebrities be sent in that direction instead?

Perhaps we could draw up a little handbook, allocating the size of their sin to an appropriate number of good works. Could Schofield be encouraged, for example, to spend his energies raising funds for the homeless or cleaning the loos in an old people's home, the promise of forgiveness on the horizon? Charities would certainly benefit.