APPARENTLY there are three signs you’re getting old – a fondness for red wine, an appreciation of olives and a no-claims bonus on your car insurance.

This trio rings true of me, but I could also add a fourth – a respect for Jamie Oliver.

When the celebrity chef first emerged nearly 15 years ago I found him unbearably smug and wanted to leave the room every time his punchable face appeared on the TV screen.

I loathed his Guy Ritchie-style cheeky Cockney act, his stupid puppy-like enthusiasm and his teeth-grinding use of the term “pukka”.

And I hated the way he kept mentioning his wife, as if any of us cared what Jools was up to. There’s nothing worse than people name-checking their partners in the media – as I was saying to my girlfriend Jenny just the other day.

Anyway, for many years I was as likely to join the Jamie Oliver fan club as Huddersfield MP Barry “he didn’t come to my committee” Sheerman.

But a few years ago I made one of his recipes for the first time. I discovered that Mr Oliver knows his onions. He knows all the other vegetables too.

Since then I’ve tried many of his recipes and found nearly all of them delicious.

I was one of those poor saps who got 30-Minute Meals For Christmas. And one of these days I’ll manage to make one of those recipes in half an hour – even if it kills me.

I’ve also come to see that his puppy-like enthusiasm, which I found so annoying when I was younger, is actually a good thing. Jamie has put his energy into good causes, particularly improving school meals.

Tonight you can see the second instalment of his latest crusade when Jamie’s Dream School is broadcast on Channel 4.

The lippy chef is trying to turn round the lives of 20 troubled teens who all left school without the magic five GCSEs.

Jamie was an academic under-achiever himself, but he thinks his all-star cast of celebrity teachers can inspire these urchins to something better in life than sitting at the back of a bus listening to awful techno music on their phones.

He’s drafted in big names like Rolf Harris, Ellen MacArthur and Daley Thompson to try and motivate the slothful, the stoned and the hyper-active.

Tonight you can see how Alastair Campbell gets on teaching the kids about politics. Apparently he starts off by promising them the class will only last 45 minutes.

The debut episode last week had some interesting moments, including Simon Callow trying, not very successfully, to share Shakespeare with the kids and Rolf getting them doodling.

But the most fascinating celeb teacher of all was Prof David Starkey, noted historian and all-round curmudgeon.

I’m only aware of the don’s work through his regular appearances on Question Time, where he comes across as a quite spectacularly spiteful man.

And there was no change in Jamie’s classroom.

“You are all here because you failed,” he announces to the kids as a way of buttering them up for a history session.

Then, seemingly without provocation, he turns to Conor – a rotund, articulate Cockney – and informs him: “You’re so fat.”

Then he tells the outraged teen: “With Jamie’s food there will be lots of dieting opportunities.”

Not to be outdone, young Conor notes that the noble professor is a little on the short side: “You’re about four foot tall, mate”.

From there things get worse, as the kids descend into slanging matches while Prof Starkey – a self-styled disciplinarian – fails to keep order.

It was not a pretty sight.

As a former teacher, I feel I should offer Prof Starkey a few words of advice about teaching teenagers.

Firstly, always have a plan. You need to be organised, to know what you’re going to do next. While you’re fumbling around for 20 seconds trying to find the right worksheet, they’ll be firing off three texts each.

Secondly, be enthusiastic. Energy is infectious – though unfortunately so is lethargy.

Thirdly, and I can’t stress this enough, don’t march in there and call one of them fat. You’re the adult, they’re the kids.

I must admit I enjoyed watching Prof Starkey struggle so much – and not just because he seems a thoroughly unpleasant man.

I liked the fact that he found it difficult to keep the class focused because it demonstrated just how hard it is to teach.

The low esteem in which educators are held in this country causes me despair, indeed I believe it’s at the root of many of Britain’s problems.

Parents, politicians and journalists don’t give teachers the support they need to do their invaluable work.

Too many people in this country believe the idiot’s maxim “those who can’t, teach”, a phrase dreamt up by someone who’s never stood in front of a class of hyper-active kids.

Best of luck to Jamie and his pals as they try to inspire the uninspirable over the next few weeks.

Hopefully, as Prof Starkey and co struggle to keep order, viewers will realise just how difficult – and how important – teaching really is.