What happened when one comprehensive let TV cameras into every corner?

While Big Brother continues its curious afterlife on Channel 5, its days as a cultural force are long gone. Young people having drunk sex under tables, the late Jade Goody bullying Bollywood starlets, and George Galloway pretending to be a cat... it all seems so Noughties now.

The real cultural legacy of Endemol's groundbreaking reality show is not to be found on Channel 5 but on Channel 4, and any number of observational documentary series in which homes, institutions and workplaces have had the Big Brother treatment and packed with wall-to-wall cameras.

The Hotel, The Family, One Born Every Minute, 24 Hours in A&E and The Model Agency have revolutionised the TV documentary with their relentless but unobtrusive scrutiny, and with their illusion (or perhaps the truth) that viewers are getting closer to unscripted and unrehearsed reality. And now, as of next week, this format is going to school.

Channel 4's Educating Essex is the most ambitious observational documentary yet made in a school.

The "bog-standard comprehensive" (in the words of its headteacher, echoing Tony Blair's infamous description) involved is in Harlow, Essex, and its governors agreed for it to be rigged with 65 cameras, so that every lesson, every staff meeting, every infraction of school rules and every pupil pulling a face behind the teacher's back, is caught on camera.

It's a candid and ultimately a heartening insight into the workings of a modern comprehensive.

But what possessed Vic Goddard, head at Passmores School and Technology College (this month, it becomes a co-operative academy), to let his school come under relentless scrutiny? Passmores recently earned its first "outstanding" Ofsted report – why jeopardise recognition with the mucky embrace of reality television?

"We serve a pretty tough community, certainly with regard to Essex... mainly white, working class," says Mr Goddard, a large, warm and jovial man unafraid to lark about on camera. "We serve areas of real deprivation. It's a tough area but I love it and the staff are so dedicated and committed to the young people here."

Harlow – since I've mentioned Big Brother – is where Jade Goody spent some of her short life and where her two boys live – but it was a different tragedy that spurred Mr Goddard to risk his school's reputation when the independent production company Twofour Broadcast came calling.

"We'd unfortunately lost one of our dear students in the months leading up to the phone call from the production company," he says. "This young man was 15 and died of a heart defect. Life's very short... don't be afraid to make mistakes... that was the mantra in the school following Jamie's death."

Passmores was selected from a shortlist of 20 comprehensives willing to be filmed. "We went for schools that either had outstanding or good Ofsteds, because we wanted to go to schools that felt confident about what they were doing," series director David Clews says. "We weren't looking to make an exposé about bad schools."

At Passmores, the final decision was left to the board of governors, and once they gave the project the green light, the enormity of the decision hit home.

"The potential for impact on the school is huge – both positively and negatively," Mr Goddard says. "It all became about trust. My default position is that I trust people – even the media – unless they throw it away."

He is an unashamed supporter of the embattled comprehensive system.

"I'm a comprehensive boy," he says. "I went to an all-boys comp in south London. I was given such support – and I think this school takes a bit of that, it puts an arm round kids' shoulders when it needs to."

He acknowledges problems – particularly an ongoing battle for discipline – but says TV shows such as this year's Jamie Oliver series, Jamie's Dream School, in which various leading lights had the opportunity to teach some unusually recalcitrant pupils, didn't offer much in the way of useful insight or potential remedy.

"We can't all be award-winning doctors or historians," he says. "I was at a conference with Robert Winston on the day after his episode aired and he was very apologetic of how it was put together and how it made it seem that a celebrity could do what a teacher does without having to work at it."

Educating Essex chiefly focuses on the 160 students in Year 11, the GCSE exam year, the school being rigged out with cameras during the autumn half term of last year. "They're not hidden in any way, but the kids got used to them very quickly," says Mr Clews.

Vandalism was a fear. "We were a bit worried that there were going to be loads of Blu-Tack put on the lenses, and we had 70 ambient microphones as well; they hang down and none of them were pulled down."

It wasn't just pupils who forgot they were on TV. "I had four cameras in my office," Mr Goddard says. "By week two, I was driving home thinking, 'Oh God, I forgot I had the cameras in there... what did I say about that?' Mind you, I think staff dress improved dramatically during the filming process..."

Staff had more important things on their mind than sartorial elegance – such as whether they would come across as proficient enough in the classroom. "The teachers were incredibly nervous," Mr Clews says. "Some didn't want their lessons filmed – they were too nervous or shy."

Perhaps with less to lose, none of the pupils opted out of filming, though a handful could not be included for legal reasons (such as their being in care). Letters were sent to every pupil, while the heavily featured Year 11 students received a home visit and counselling from an independent psychologist.

The show's transmission was deliberately delayed until after the Year 11 students received their GCSE results last month – many of them having gone on to study at the nearby sixth-form college. It was important, Mr Goddard says, that any aftercare continued there. "The production company are still in contact with the ex-students now, making sure they're being sensible with the social media, because that's a worry," he says.

There is an ethos of second and third chances at Passmores that may strike some viewers as over-forgiving – especially those who blame schools for everything from riots to illiteracy. The head, however, is proud of the school's unwillingness to resort to permanent exclusion, a drastic "solution" which Mr Goddard calls "morally wrong".

"I know there will be certain individuals in the media who will be thinking we're too liberal and that we should just be kicking these kids out – but you kick them out and where do they go? I'm very proud that we serve a tough community, but we serve them every day and give them more and more chances.

"Ultimately the national public is less important to me than what my local community thinks. As long as they think we're still trying to do the right thing by everybody then that is all that really matters."

I'd say the local community is very lucky in having Mr Goddard and his staff to teach their children. And whatever you think of some of the educational abilities on display, if my daughter were at Passmores, I'd think that she was in good hands and that she had every chance of passing a happy and productive time at school.

'Educating Essex' is on at 9pm,

Channel 4, 22 September