Like many people, I feel very sorry for Gary McKinnon, the computer geek who admits hacking into Pentagon networks and posting a note remarking that its security was “crap”. McKinnon is a UFO-obsessed fantasist with Asperger’s syndrome who believes in little green men. Extraditing him to America to serve a possible life sentence in a supermax jail would be about as civilised as those 18th-century Hartlepudlians hanging a monkey on suspicion of being a French spy. Wrong though his actions were, McKinnon has at least taught us that it’s never a good idea to have the word “password” as your password, especially if you, er, work for Nasa.

But here’s what’s slightly puzzling. An impressive group of A-list supporters has gathered behind McKinnon comprising senior MPs, the London Mayor, the Daily Mail and celebrities ranging from Pink Floyd’s David Gilmour to Trudie Styler, wife of Sting.

Styler, you will have noticed, was the blonde clamped to the shoulder of McKinnon’s mother Janis on the steps of the High Court recently, meaning that her concerned, lovely face was in every camera shot. One of the main reasons that these campaigners cite for McKinnon, 43, not being extradited (or, if convicted in the US, being repatriated here to serve any sentence) is that he is a vulnerable person and a real “suicide risk”.

Mmm, I don’t doubt it. But is it churlish to point out that there are plenty of people shoved into British prisons every week with mental health issues who are at even higher risk of topping themselves? Some hang themselves with bed sheets, choke themselves on toilet paper, nasty stuff like that. Some of them are teenagers. If celebrities and MPs truly are concerned about suicidal prisoners maybe they could find time in their schedules to campaign on behalf of them?

David Blunkett, another of McKinnon’s supporters, will know what I mean. He was the Home Secretary when Petra Blanksby, 19, throttled herself with a ligature, thought to be a shoelace, while on remand at New Hall Prison, Wakefield. Her death wasn’t terribly surprising — she had tried to kill herself 92 times before and had been self-harming since the age of 12. Still, she was banged up on a charge of “arson” even though the thing that she had tried to set fire to was herself and she had no previous convictions. No offence to Gary McKinnon, but I find this more of an outrage.

But that’s the thing, isn’t it? Some cases seem to touch high-profile hearts and others just don’t. Global warming or anything commanding an international stage seems to have no trouble roping in celebs and groovy politicians. We all remember David Beckham and Girls Aloud sultrily clicking their fingers on the Make Poverty History videos, and Madonna at Live Earth ordering us to jump up and down to “save the planet”. And yet a year after the 7/7 London Tube bombings commentators noted the absence of any celebrity support group or concert for the limbless victims. I doubt yesterday’s news that Cookham Wood Young Offender Institution has been deemed seriously unsafe for vulnerable young people will cause much public hand-wringing. To my knowledge no one famous rushed to cosy up with, say, the family of Adam Rickwood, 14. When he hanged himself at Hassockfield Secure Training Centre, Co Durham, in 2004 (again on Blunkett’s watch) Adam became the youngest child to die in British custody in modern times. But no rubber bracelets for him.

Similarly, I can’t believe that the whole country isn’t up in arms over Michael Shields, 22, now serving a ten-year sentence in Warrington for a crime that a blind man in a peasouper could see that he didn’t commit. A Bulgarian court convicted Shields, a Liverpool FC fan, of the attempted murder of a Bulgarian citizen even though another man had confessed and there wasn’t a credible shred of evidence against Shields.

Fair Trials International has called it a travesty of justice, the most senior lawyer in Bulgaria concedes that there are doubts about his conviction and the High Court has ruled that Jack Straw has the power to pardon him. But he refuses.

Shields, understandably, isn’t in the most robust health. And yet with the honourable exception of local MPs and local celebrities, Shields’s case hasn’t provoked a fraction of the national fury that McKinnon’s has.

Perhaps parochial issues are deemed insufficiently fashionable. A kid from a council estate eating razor blades in a Yorkshire slammer, after all, doesn’t quite carry the world kudos as Gary McKinnon versus President Obama.

Because, of course, there’s another strand to McKinnon’s cause: it highlights our unfair extradition agreement with America (signed by one, erm, David Blunkett). I agree that this treaty is worrying, but then — and I hate to sound all worthy — so is the suicide of vulnerable young people on our own doorstep.

In the film Brüno, Sacha Baron Cohen’s vacuous Austrian protagonist is desperate to up his profile by latching on to a “cool” cause or, as he puts it, “a new shithole to save”. But he can’t decide which one because “Clooney has got Darfur, Sting has got the Amazon and Bono has got Aids”. Although the world knows that these three are sincere about their causes, it’s certainly voguish now to have a charity or two under your belt.

But as Baron Cohen’s monster demonstrates, for some celebs picking the right one is akin to choosing the right Hermès accessory.

Proving the point, Inquest, a fine British charity that supports the families of those who die in custody, is struggling badly for funding. But, as it says, the issues it deals with are not considered “sexy”. Furthermore, to many MPs, the vulnerable-prisoner debate is simply not a vote winner.

I’m not suggesting for a second that Gary McKinnon doesn’t deserve his A-list support and I hope that he is not extradited. But he is far from the only person being dragged through the judicial system in a vulnerable mental state. If only his glamorous friends could share their love around.

I cannot sign off without saluting Sarah Palin’s moving denial of internet claims that she and her husband Todd are about to divorce. “Divorce Todd?” she said. “Have you seen Todd? I may be just a renegade hockey mom, but I’m not blind!” Aaah, bless. It’s true that we don’t hear the word “no” in there, or “love”, come to think of it. But I’m sure that Todd feels reassured that she puts such a premium on his looks. Let’s hope that he cleanses, tones and moisturises and knows that it’s never too late for an anti-wrinkle pillow.

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