In May 1897, Oscar Wilde composed a letter to the editor of the Daily Chronicle on the subject of child prisoners. "Of course," wrote Reading Gaol's most distinguished ex-offender, "no child under fourteen years of age should be sent to prison at all. It is an absurdity, and like many absurdities, of absolutely tragic results."

If it was an absurdity to enlightened Edwardians, it is undeniably tragic, now, to think that in more than a century the debate has "moved on" from the fact of child prisoners to the legal niceties of their position. This week, the chief executive of Barnardo's, Martin Narey, blew the whistle on the shocking numbers of children serving custodial sentences in England and Wales. When it comes to banging up kids, it seems, we are outstripped only, within Europe, by Russia and Ukraine. More shocking still, Barnardo's estimates that 170 children sent to custody in 2007/8 were wrongfully detained.

Government guidelines suggest that, for children under 14, only those who have committed a grave crime, eg murder or rape, or who have committed serious crime and are deemed to be persistent offenders should be locked up. More than a third of the 12-, 13- and 14-year-olds surveyed for the Barnardo's report failed to meet these criteria.

When you consider the personal circumstances of these young offenders – just under half the children in custody had been abused, more than a third had been living with a known offender, and more than a third had witnessed violence in their own families – their swift excision from society seems harsh indeed. Nor, it seems, does society stand to benefit.

Narey, a former director general of the Prison Service, knows more than most about the effect of custodial sentences on youngsters. "In terms of their reoffending, or doing anything to protect victims," he points out, "it is almost invariably ineffective."

There's bleak justice in the fact that the Barnardo's report should appear in the week that public anger over the death of Baby Peter comes rolling back to the boil. Narey pulled down fire and brimstone on his head last November when he suggested that the murdered toddler, mourned with a mountain of teddy bears from people he never knew, was exactly the kind of neglected and abused child who classically goes on to become a young offender.

We are always ready to weep for abused innocence, yet 10 short years' experience from toddlerhood to adolescence is, apparently, enough to place a child beyond the high, spiked pale of our concern. Wilde would have been been acquainted, though scarcely, one imagines, in sympathy, with the notion of children being seen and not heard. He would surely be horrified at the refinement of a society where children are "disappeared" the minute damage begins to show.

The awful, civic tidiness of locking troubled children away is weirdly mirrored by the week's other news story that only 49 per cent of parents are willing to let children aged between five and 10 play unsupervised at their own front door, while children as old as 14 have no idea how to get to school under their own steam. The Living Streets survey suggests that parental fear – of traffic, of violence, of strangers – has effectively placed British children under house arrest.

It's the kind of status quo that everyone agrees is a terrible shame and few dare to defy. Both my own children, aged 13 and 11, walk to school on their own but it was, if I'm truthful, a long-awaited privilege, assiduously prepared for and conferred, with some ceremony, on their 10th birthday. They're allowed to go to the park and knock about selected local streets within a slowly expanding radius, while other streets in our typically patchy corner of north London remain a no-go area. It's hardly Swallows and Amazons, but at least there is a sense of growing independence and, crucially, an element of risk management. Because we cannot expect adolescents to sprout responsible judgement like body hair. Like every useful value, it's a learned response.

Clearing the streets of children – whether it's because we're alarmed for them or alarmed by them – is not the answer. To coop a child in the home or in legal custody is physically to deny them the chance to change and learn and engage with their community. And refusal to engage makes prisoners of us all.

Oppression doesn't always come with a veil

On a recent trip to Jordan, I was interested to see a group of Muslim women splashing, fully clothed and veiled, in the Red Sea. They didn't look particularly oppressed by their outfits, nor did I consider stripping off to a bikini and jumping in among them. (There are designated beaches where Westerners can dress as they please.)

So it's hard to know quite what to make of the case of the young Muslim woman barred from a swimming pool on the outskirts of Paris for wearing a "burqini".

I don't find a lot to applaud in France's militant stance against the veil. I'm not sure it's useful to get hung up on dress codes when there are more urgent questions of women's civil rights to be addressed (divorce and child custody rights spring first to mind) in some Islamic countries. On the other hand, I can't imagine there's a precise Koranic injunction relating to the "burqini", which looks very much like a wet suit with modesty frills and might almost have been designed with a political test case in mind. Given the sensitivities involved, I'd as soon not build the incident into the cause célèbre clearly desired on both sides of the dispute.

One thing I do know. Faced with pictures of Tess Daly (left) flashing her washboard stomach in a bikini 10 weeks after giving birth and breathless advice from every quarter on how to achieve a similar look (all you need is a personal trainer, endless cash and endless childcare), I'm losing the will to live. There's more than one way to oppress a girl with swimwear.

Come dancing – if you can find a place

The appointment of Arlene Philips, lately of Strictly Come Dancing, as a government-sponsored "dance tsar" may indeed be the very thing to get the people of Britain up and shaking their maracas.

Or it might be yet another expensive, opportunistic, celebrity-driven gimmick masquerading as health policy. (Given the number of swimming pools and sports centres that are closing across the country for lack of funding and the fact that, post-Strictly, dance classes across the country are already full to bursting, a cynic might incline to the former.)

Those of the sedentary persuasion may take comfort from the wisdom vouchsafed to me in my youth by an elegant old socialite observing my progress at a county ball. "After the age of 25," she whispered to me, with some urgency, "nobody can make you dance."