Last Night's Television: Bruce Forsyth: A Comedy Roast, Channel 4<br />Embarrassing Bodies: Charlotte's Story, Channel 4

The point about a comedy roast – spectacularly missed by the newspapers who indignantly reported on Jonathan Ross's insulting remarks about Bruce Forsyth recently – is that the guest of honour is on the spit. An essentially American institution, in which showbiz entertainers gather for what the Scots would call a flyting – or an insult contest – the whole idea is that you let them have it with the best you've got. Offence and embarrassment don't have an invitation, since the only breach of good taste at such events would be to serve underarm because you thought the recipient couldn't handle anything tougher. What's really interesting about them, though – apart from the occasional pre-prepared aces – is that embarrassment is always lurking about there somewhere, waiting to pounce on the possibility that a friendly insult might have strayed just a little too close to a nerve. And in the first of Channel 4's Comedy Roasts it looked to me as if embarrassment was spending quite a lot of time near Jimmy Carr and Jonathan Ross.

In Bruce Forsyth: a Comedy Roast, the gags about Bruce were fairly predictable, even if they were nicely turned now and then. There was a lot about the longevity of his career, naturally. "Brucie is the greatest performer of his age," Jonathan Ross observed. "I can say that because all the other performers of his age are dead". There were gags about the cheesiness of The Generation Game, about Strictly Come Dancing and about short-term memory loss. And Jimmy Carr got a nice ad lib after suggesting that the repetitions in many of Forsyth's catch-phrases were just a cover for senior moments. "That's true... that's absolutely true," chuckled Brucie from the sidelines. "See," said Carr, "he's done it again."

What was really interesting, though, was the genuine steel occasionally perceptible amid all the rubber daggers, never against Forsyth but against other comedians in the room. In the case of Jonathan Ross, it was, I think, affectionate, even if he might now regret his own gag about only turning up because he wanted to butter up Channel 4 "in the hope of future employment". "Surprising you turned up in person, Jonathan," said Sean Lock, "because normally when you're going to insult an elderly national treasure you do it on the phone." So many people had a crack at Ross, in fact, that Forsyth ended up complaining. "Is this my roast or not?" he asked, shortly after Jack Dee had taken his turn at putting a loving boot in.

It can't have been comfortable to be Jimmy Carr, though, more than once the recipient of a crack that seemed to have a bit of heft behind it. John Culshaw introduced him as Jimmy Carr CBE, a mysterious allusion that had either lost its punchline because it was too obscene to broadcast, or never had one because it was a joke he wasn't in on. He looked oddly taken aback and even more so when Jack Dee explained that his waxwork at Madame Tussauds could easily be identified because it was the one with the Do Not Punch sign in front of it. All in the spirit of the evening, of course, but it was a spirit with a hidden kick in some cases.

Embarrassment is the raison d'être of Embarrassing Bodies, though less so in last night's extended special about Charlotte, a little girl who had delivered a particularly memorable unveiling a while ago, peeling her socks off to reveal a terrifying set of veruccas that looked as if they were auditioning for the new series of Doctor Who. Even the unperturbable Dr Christian was speechless, and the cogs audibly whirred as he tried to find something tactful to say.

They seem to have whirred to good effect. "Have you ever checked her immune system?" he'd asked Charlotte's mother in the original programme. "This is a virus that's winning." And no, Sophia hadn't checked Charlotte's immune system, and when it was checked they found that it wasn't all there. The painful excrescences on her feet were suddenly reconfigured from cruel torment to a helpful warning signal. Quite why none of Charlotte's previous doctors had heard a klaxon go off in their ears when they caught sight of her foot wasn't explained but now, a little belatedly, she could get the bone-marrow treatment that would probably save her life.

That, I take it, was why Embarrassing Bodies: Charlotte's Story was on at all. It was proof that a programme that has sometimes been treated as an ignoble freak show really might have a serious medical purpose. It might as well have been titled "We Saved a Little Girl, So There!" And, naturally, it was as compelling as all accounts of childhood suffering are – a plot line you can't turn away from because you hope so fervently for a happy ending. I'm glad to say Charlotte seems to have got it.