He’d like to teach the world to cook… Jamie Oliver talks to Richard McComb about his latest mission.

In a few weeks’ time, Jamie Oliver, TV chef and food evangelist, will be greeted like a pop star when he entertains the crowds at the BBC Good Food Show at Birmingham’s NEC.

Jamie will provide tips and tuition and wok-loads of banter. Everything will be good humoured, interspersed with cheeky jokes and nod-nod, wink-wink asides.

And that’s because Jamie is a fun guy, arguably the nation’s favourite telly cook (sorry Gary, but it’s over, get used to it).

He’s a down to earth geezer who happens to know his onions – and his kohlrabi – very well indeed.

Except that is only half the picture.

Despite the schoolboy smile and jolly demeanour, Jamie Oliver is also a very easy target for the critics. He wears his heart on his chef’s sleeve and that makes him vulnerable and has prompted, as he tells me, some bleak times, f***ing bleak.

Interviewing Jamie (it’s not right calling him Oliver) is a surprise because he is as passionate as you hoped he might be but feared he wouldn’t be.

He claims not to court controversy – it is just that the subjects he tackles in his documentaries are controversial. The media fall-out from his School Dinners programme, in which he laid bare the Turkey Twizzler Generation, went to the top of the political agenda.

Jamie’s Fowl Dinners exposed the cruelty and filth of the mass market poultry industry where miserable chickens are sold for £2.50.

Now his Ministry of Food project, a School Dinners for grown-ups if you like, has put the wind up verbose middle-class commentators who have accused Jamie of hectoring fat Northerners and patronising their dim-witted attempts at basic cookery.

Jamie used the four-part show, set in Rotherham, to trial his pass-it-on-pledge – getting adults incapable of boiling water to master recipes and then “pass them on” to friends and colleagues, a trickle-down system of culinary education.

It’s either a glib gesture or a heart-felt attempt to solve the nation’s obesity epidemic, depending on which side your bruschetta is buttered.

So did Jamie expect the holier-than-thou backlash?

There is a resigned, world-worn inflection to his voice. “No, not really. No,” he says.

If there is a trace of self-pity, it does not last for long. Detractors (including “rent-a-gobs”) have gone as far as suggesting Jamie and his production team deliberately picked on jobless, ill-educated, gut-buckets to stereotype a whole class, poke a bit of fun.

He’s not having that.

“At the end of the day, I pride myself on clarity, honesty and no nonsense,” he says.

“If truth be told, there is a complete cross-section of health, age, employment [in the show]. There are only two people out of 15 that are unemployed, only one person who is classed as overweight or obese.”

Later, Jamie returns to the theme, because it bugs him: “I gain nothing from it [the show] being biased. Nothing. Anything. Because people are clever and I will get turned over. I feel confident about what we have done.”

He admits to questioning himself, looking at his own motives: “I have got to sleep at night. I have got young kids. I don’t want to open my gob and talk b******s.”

Despite the millions in the bank – he tells me he could have retired at 23 – Jamie is stung by personal criticism. If I was him, I’d jack it in, milk the Sainsbury’s adverts and put my feet up. So doesn’t he ever think about calling it a day, give up asking the awkward questions?

Again, there is that weary voice. “All the time. All the time,” he says.

“I didn’t have to make Ministry of Food. I had just come out of doing Jamie at Home. It was the nicest, most pleasurable, easiest programme to make about me growing stuff and cooking stuff.

“School Dinners was the darkest two years of my life. It was f***ing miserable at times. It was upsetting, it was hard. It was hard to get clarity through government or through local authorities.

“Being called all sorts of names every single day by kids when you are just trying to sort them out is a little bit demoralising.”

There is something that drives him on, though, and he seems genuinely surprised by his own celebrity longevity.

“I found myself in this strange job. Normally, this job eats you up and spits you out in three years.

“I’ve had the pleasure of working with great people and at the end of the day it is about doing something that has substance and can offer a better life in some way, shape or form to people.”

Class, or money, or lack of money, has nothing to do with people’s food choices, he insists.

“I don’t really understand class. Let’s call it available cash,” says Jamie.

“I know City boys on a couple of hundred grand a year that are eating the same s*** as people that are on the dole.”

“Ethnicity and demographic background has nothing to do with the real problems we have.”

Surely people know when they are eating rubbish, though, like the individuals in Ministry of Food who lived off takeaway kebabs and 10 packets of crisps a day. Isn’t it time people started taking some personal responsibility and stopped playing the victim card?

“There are many, many people you can blame,” says Jamie, who professes to have no interest in a political career.

“Yes, of course, there is personal responsibility. But I also think that if you have never been involved at school, or in your home life, in any kind of food then you are going to be naïve and ignorant about it.

“Some people might take that as being thick, or some people might just be realistic and say, ‘Well, they have never been hooked into it.’

“You have got to understand the basics of it [cooking], like riding a bike or anything else, otherwise you are going to fall over…

“It’s a cocktail of many things. It’s a cocktail of school dinners being put out to private caterers in 1986. It’s to do with not having cooking taught effectively, or hardly at all, to our young children at schools.

“It is about school playing fields getting sold off. It’s about the rise of frozen food and the sheer volume of takeaways available.”

The scale of the problem is huge – Jamie says there is a Rotherham within a mile of everyone – and he believes supermarkets have a “massive, massive responsibility not just to flog stuff but to encourage and teach and inspire.”

Educating people, not collective shoulder shrugging, is the key. In many families there simply is not a culture of cooking, says Jamie. It is pretentious to think these people should know better if they have never been shown how to knock up a shepherds’ pie.

“And if they haven’t been shown, they don’t [cook], they really don’t. If people haven’t been shown, or they are vulnerable, or they don’t know what to do, they can’t have a relationship with food and they will do silly things and make bad decisions,” says Jamie.

“Yes, people know that eating loads and loads of burgers is bad for them day after day. But if they haven’t got the tools to make better decisions then they are sitting there stuck ...

“Look, I don’t take pleasure in doing these things. They are quite hard. Deep down at my core my personal belief is that the only reason these things work is because I haven’t lied to the public and I have a true, genuine story to tell. I hope the public don’t feel I have ever let them down and would lie to them.”

* The BBC Good Food Show is at the NEC from November 26-30. For tickets call 0870 040 0388. Go to www.bbcgoodfoodshow.com