In the old days, people simply did not want to go to St Thomas the Apostle College. Such was its reputation, in fact, that even the current headteacher did not want to go there.

“I’d stupidly registered with a few headhunting agencies,” says Eamon Connolly, who at the time was deputy headteacher at Mossbourne Community Academy in East London, under future Ofsted chief Sir Michael Wilshaw.

“They said, ‘Do you fancy being head of an all-boys’ school in Peckham?’ I said, ‘You have to be kidding.’”

St Thomas the Apostle (“Stac” to those who go there) was everything that one would expect from an all-boys’ secondary in this historically deprived area of South London. The school was bottom of the borough’s league table for achievement, but top for juvenile crime.

Though Stac has space for 150 pupils in a year, in 2012 there were only 67 boys in Year 7. That same year, only 42 per cent of pupils achieved five A* to Cs at GCSE.

In 2016, 81 per cent of Stac boys attained five good GCSE passes, placing it second in the borough’s league table, behind a girls-only secondary. It had its first appeal over places. And, last month, the school was named Tes secondary of the year.

This was not something that the current sixth form could have foreseen when they started Year 7. “I used to say ‘I go to Stac’ like I was embarrassed,” says 17-year-old Emmanuel Otobo, who is sitting with friends in the dining hall.

“Other people would say, ‘Ugh, Stac boys,’ and you knew what they were thinking. Like, that you were low achievers, like you just weren’t focused. They thought that you were coming here for some kind of social life.”

‘It was about making a difference’

Most of the boys live on nearby council estates; in at least one case, a family of four lives in a single room. Many pupils are recent immigrants, and speak English as an additional language. When teachers took pupils on a day trip to see the skyscraper The Shard, several boys pointed at the Thames and asked whether it was the ocean. Peckham is fewer than three miles from the Thames.

But it was precisely these boys who changed Connolly’s mind, after his initial reluctance to consider the Stac headship. “I was just hooked,” he says, of his first visit to the school. “Talking to the boys is something quite special. The reason I got into education was to make a difference. Although the first days here were tough, it was very much about making a difference.”

When Connolly took up his post in 2012, the school was under threat of closure; the only reason it stayed open was because money had already been ploughed into new buildings for the school.

Today, the site is spread-out and airy. The school is deliberately low-rise - the aim, Connolly says, is to provide a counterpoint to the tower blocks where many of the pupils live - and many classrooms have one wall made entirely of glass.

A boy strolls past, and Connolly greets him by name. Fifteen-year-old Dillon Oppon-Ferguson is tall, with a good three inches of hair adding to his height. Next year, he will be Stac head boy, but his ambitions stretch much further than that. “I’m going to be an equities researcher in a bank,” he says. “I’ll do that for 10 years, maybe 20 years. Then I’ll become governor of the Bank of England. Then probably after that I’ll retire, because what do you do after you’ve been governor of the Bank of England?”

Connolly walks on, pausing at a collection of noticeboards near the dining hall. This is one of the methods - possibly the most controversial - he uses to drive up standards at the school. Each pupil is ranked within his year group, both for individual subjects and for overall achievement. (Boys with special needs are not ranked.)

Connolly points out that the ranking system helps pupils to identify areas of weakness: if, for example, someone regularly comes in the top 20 for most subjects, but is ranked 80th in the year for geography, it is easy to see that geography is the subject that requires most work for that student.

“Like anything, it’s how you manage it,” Connolly says. “We focus on movement: moving up the ranking. It’s about being open and honest with the boys. And I think that they respect that.”

In the dining hall, Emmanuel’s friend Anthony Amyamjor, 17, immediately defends the ranking system. “It makes you work harder,” he says. “I always came around the 13, 14 spot, and I really wanted to hit the top 10. I ended up number five, in the last ranking before my GCSEs.”

Moving on from the noticeboards, Connolly walks around the school, dipping in and out of classrooms. Each time he enters, the class stands up and greets him; each time, he addresses several of the boys by name. “How would you describe this school?” he says, on more than one occasion. The response is always the same: “Strict.”

This is a deliberate part of the school culture. First thing in the morning, all boys line up in alphabetical order, and then march indoors together. The importance of uniform is emphasised repeatedly.

‘Discipline is key’

Emmanuel and his friends reflect on this. “Strict is actually a good thing,” he says. “Discipline is key. It moulds us into the young gentlemen that we’re becoming today.”

Next to him, Anthony straightens his suit jacket. “When we get into the real world, when we have a task, they expect that task to be completed, and to a high standard,” he says. “So we’re getting used to it.”

Cos Smart, the deputy head in charge of behaviour, finds this understanding of the importance of discipline immensely gratifying. “There’s a public expectation that these kids are going to be gang members and dealing drugs,” he says. “But very much the opposite is true. Looking after behaviour has gone from being one of the hardest jobs in the school to one of the easiest. Because the kids want to be learning. They understand the value of learning. So why would they stymie their own chances?”

Many, he says, now dream of going to university: this year, four pupils were interviewed for places at Oxbridge, though none were successful. “Because we’re strict about the little things, we don’t have to worry about the big things,” Smart says. “As a school full of boys, we should have one of the highest exclusion rates in the country. But - touch wood - we’ve had one exclusion in the last five years. If we didn’t have such a structured environment” - “structured” is Connolly’s preferred term for “strict” - “that wouldn’t have happened.”

This is a lesson that Connolly says he learned during his years working for Sir Michael. “That focusing on the basics was something we did at Mossbourne,” he says, strolling through the playground at the end of the day. Around him, boys stream out of lessons and on to the football pitch for a kick-about.

“And high expectations. No limitations. We believe that, if you put good teachers in front of motivated students, and give them the resources to deliver, then the rest will take care of itself.”