Team is parachuted in to raise morale and marks at St Aldhelm's Academy in Poole

Three years ago St Aldhelm's Academy had the worst GCSE results in the UK and was temporarily closed after a damning Ofsted report called it 'dysfunctional and unsafe'

The right formula? St Aldhelm’s Academy has been taken over by Ambitions Academy Trust, which is hoping to improve it (Russell Sach)

The cavernous space echoes with voices as we walk down the a vast central passageway. In open areas lining the walkway, young people gather with varying degrees of attentiveness. The combined murmur of voices is amplified and distorted by the building, providing a kind of background interference. It's an oddly distracting sensation. But then this is an odd place. It's not the massive concourse of a train station or a shopping mall. It is, in fact, a school, and this huge, open-plan space is where all the teaching happens. And if I think the noise is distracting now, I should have heard it before the current management came on board.

Things were certainly quieter in early February when St Aldhelm's Academy, Poole, was forced to close for three days to all but year 11 students due to staff sickness. Already in special measures, the school's first day of closure coincided with an unannounced Ofsted inspection. The subsequent report was damning, calling the academy "dysfunctional and unsafe" and revealing that pupils "cause havoc" by running around the corridors during lessons and that "verbal abuse of staff is common, with some physically assaulted".

"It must have seemed wonderful when it was designed," says my guide. "Twenty-first century learning and all that. But I haven't shown a single person around who thinks this is a good idea." This is Brian Hooper, chief executive of Ambitions Academy Trust, the new sponsor parachuted in after the closure and the man who, along with new principal Sian Thomas, is largely responsible for the relative calm.

The open-plan teaching areas are designed to hold up to five classes at a time, Hooper explains. At its worst, that could mean two spaces with five classes each on the ground floor and the same on the first floor, all opening out onto the central corridor, or "the street", as it's aptly named. At the moment, there are only two classes in each space – one of the firefighting measures that Hooper and Thomas have put in place to restore order. I look around and try to imagine what it would look and sound like if they were full. The image brings an involuntary shudder.

But is the design the only reason behind the academy's woes, or just the surface symptom of a deeper malaise? The £10m open-plan space was constructed in 2013, but was only one in a long series of mistakes and failures. If a school's lack of success can be gauged by the number of times it has undergone "rebranding", then St Aldhelm's is right up there. Starting life in the 1930s as Kemp Welch Senior School, it underwent the minor transition to Martin Kemp Welch, before being put into special measures and renamed Rossmore Community College in 2000.

In 2008, after a brief upturn, the school was given a further notice to improve and, in 2010, it became St Aldhelm's – Poole's first academy, with government funding of £21m and sponsorship from the Diocese of Salisbury and Bournemouth University. Just one year later, the new academy posted the UK's worst GCSE results, with only 3 per cent of students achieving five A-C grades. In 2012 and 2013, results improved to 28 per cent and 31 per cent respectively, but in 2013, disaster struck again when the school lost £1.1m in an online scam that saw administrative staff hand over the school's bank details to email scammers.

After that, problems seemed to snowball, with principal Cheryl Heron quitting, sponsor Bournemouth University pulling out and the school being given a financial notice to improve by Ofsted. It soon became the school that no one wanted to touch, with an interim leadership team and a remaining sponsor that soon confirmed that it, too, wanted out. GCSE A-C results plummeted again to 17 per cent and the academy was put back into special measures.

Headteacher Sian Thomas and chief executive Brian Hooper (Russell Sach)

One of the problems facing the school, according to a local councillor, Tony Trent, is a lack of self-worth that has slowly become endemic in the children, many of whom come from two local housing estates – Alderney West and Bourne Estate. "One of the big problems is aspiration," Trent says. "I've talked to some of the youngsters and they say, 'Oh we're rubbish. We live in a rubbish area. We'll never get anywhere'. There's a culture of defeatism."

For Jane Ford, a parent who lives in Alderney West, there is frustration at the perceived lack of accountability of academies such as St Aldhelm's. "Who can parents chase if they want to get something changed?" says Ford, who has three children.

Others say that the preponderance of grammar schools in the area – there are two in Poole – has a negative effect, both on league-table results and in creating a two-tier system that is damaging to morale. Trent says: "It's about creating an environment where people aren't made to feel that if you failed your 11-plus you're a second-rate kid."

As someone who grew up on Bourne Estate, this is the school I would have gone to if I hadn't passed the 11-plus. As such, I saw the partitioning effect of grammar schools from the other side. I was labelled a snob by my friends on the estate, who in their own way were vocalising a quite valid point about the elitism that grammar schools create. Do I think that they felt in some way devalued by the experience of not being selected for special treatment based on one small aspect of their total worth? Yes, along with Trent, I do.

Whatever the wider reasons, everyone is in agreement on one thing: the problems have spiralled out of control in the past 12 months. Since the last permanent head left and the sponsors either pulled out or proved unwilling, the school has languished in a kind of interim limbo where standards, discipline and morale slowly sink through the floor. Parents speak of detentions being handed out arbitrarily, an increasing culture of exclusion, staff shortages through resignation sickness or stress, and a lack of communication with parents. "It used to have a nice community feel to it," Ford says. "But then it became a very closed shop. Nobody knew what was going on."

As things slipped, staff shortages through sickness and stress increased, until children were reporting an increasing number of lessons without teachers. "There's usually not enough teachers to run the school," one Year 11 student told the Bournemouth Daily Echo in February. "There was a Year 7 class and they didn't have a teacher, so one of the Year 11 students had to teach the class," her friend added.

All of this culminated in the three-day closure of the academy in February due to staff shortages and health and safety concerns. It was a crisis that precipitated swift action from parents and politicians, including the local MP Conor Burns, the regional schools commissioner, Sir David Carter, and senior figures at the Department for Education. The new sponsor, Ambitions Academy Trust, which already runs three schools in the area and has a good record for turning failing schools around, was brought in – it had already been in talks about taking over, but following the closure it was brought in to start immediately. Funding was quickly made available to begin the job of rebuilding, in every sense of the word.

"We need to get proper classrooms back in," Hooper explains to me in an office in the academy that, blessedly, has its full complement of windows and doors. "We are going to get six classrooms downstairs and six classrooms upstairs – proper classrooms with walls and doors put back in again." The Department For Education and the Education Funding Agency is moving incredibly quickly and building work is due to start in June and end in September. In the meantime, the open-plan classrooms have been limited to two classes at a time and the Year 11 students have been moved to a separate building.

The firefighting is, perhaps, done. Next will come the harder job of changing ingrained ideas in the students themselves. "It's about building up the trust of the parents and the community," Thomas, the new principal, says. Hooper adds: "Our mantra is that high expectations lead to high achievers, and we constantly reinforce that. As the self-esteem grows, the aspirations will grow."

It is a thought I try to hold on to as I leave the building and its huge echoing space. As I approach the exit, a student is heading for the door at the same time. He stops, pulls it open and waves me through with a smile. I look around suspiciously. Has this been somehow orchestrated? But it doesn't seem so. It seems this is just a happy student with the confidence and self-esteem to be positive. If so, he is a perfect symbol of what this school is just beginning to aspire to.