Every so often, Jonny Mitchell will be in the pub or in the supermarket and a stranger will start staring at him.

“I know you,” the stranger will say, eventually. “We were in school together, weren’t we? Or did we play rugby?”

“No,” Mr Mitchell will reply, slightly embarrassed. “You know me off the telly.”

A year ago, Jonny Mitchell was known to his staff, his students and his local community as the headteacher of Thornhill Community Academy. Then came Educating Yorkshire, the fly-onthe-wall Channel 4 series watched by millions. And now he is television’s Mr Mitchell, recognised around the country.

“Someone on Twitter wrote, `I saw Mr Mitchell in the supermarket the other day. He was fat,’ ” he says. “It took some getting used to. If I’d ever considered having an extramarital affair, I couldn’t now. So it has its drawbacks. Or are they advantages?”

The success of Educating Yorkshire outstripped even that of its predecessor, Educating Essex. At its peak, the show attracted four and a half million viewers. Even initially sceptical TV critics were won over by the end of the series. “They were saying, `They should all be knighted’, and things like that,” says Mr Mitchell. “Nothing’s happened about that. I’m still waiting.”

A new series, Educating the East End, set in a London comprehensive, will begin on 4 September. In advance of that, Educating Yorkshire One Year On was screened this week, offering a potted update on many of the characters featured in the series. So the cameras followed students Hannah and Sheridan as they received the results of their fifth GCSE maths resit. They also visited Georgia, who is adjusting to life as a teenage mother, and schoolboy Ryan, still on a mission to become prime minister. (Mr Mitchell offers this spoiler: “He hasn’t yet.”)

It was also announced this week that another star of the show, Musharaf Asghar, who was shown working to overcome his stammer, has been given his own spin-off programme Stammer School: Musharaf Finds His Voice, to be screened on Thursday 28 August.

Then there is the impact that the programme has had on Thornhill. The school had previously always struggled to fill its places; this year, its new Year 7 will be filled to capacity. In addition, around 50 students transferred mid-year from other schools.

“The programme served the purpose of raising the profile of the school,” Mr Mitchell says. “My main aim was to do whatever we could to give our kids and our school and our community every possible advantage. If this gives us more opportunities to provide for the kids, that has to be the goal of anyone going into the headship. But it’s not done my reputation any harm, either.”

Since the programme aired, he has fielded a range of requests for personal appearances, including one to open a supermarket. “It wasn’t even in my local area. It was, `Will you come down south and open a supermarket?’ No, I bloody won’t.”

He has also been asked whether certain members of staff are married or single. “I’ll say, `Yes, they’re married, but I’m sure they’ll like the attention.’ ”

In fact, he has limited the invitations he accepts to those that help to promote the school, the series, or education in general.

But he did meet the teachers of Frederick Bremer School, in East London, to advise them on what to expect when Educating the East End makes their school as familiar as Thornhill to the TV-viewing public.

“They wanted to satisfy themselves that they weren’t in for a nasty shock,” he says. “We gave the advice that, if something comes along, then grab it with both hands.

“Every single decision taken by every single individual in every episode has the potential to cause controversy. But we’re moulding young adults. We’re not instructing any more these days. We’re educating, and I think there’s a difference.”

And, he adds: “Don’t be scared. It has to go terribly, terribly badly to have an adverse impact on your school.”