Amid the myriad joyful images on social media, showing ecstatic pupils and their teachers celebrating GCSE results, one particular success story stood out.

Michaela community school, a controversial free school known for its strict behaviour policy, picked up its first set of GCSE results on Thursday, five years after opening its doors to its first pupils.

“Michaela pupils SMASH it,” tweeted the headteacher, Katharine Birbalsingh. Her colleagues were similarly delighted. “I’m so proud to be a Michaela teacher today,” tweeted the maths teacher Thomas Kendall. “It feels like winning the league. The kids deserve it so much for all their hard work.”

Compared with other non-selective state schools, Michaela’s results rank among the best in the country. More than half (54%) of all grades were level 7 or above (equivalent to the old-style A and A*), which was more than twice the national average of 22%. Nearly one in five (18%) of all grades were 9s, compared with 4.5% nationally, and in maths, one in four results were level 9.

Birbalsingh’s Twitter feed documented her morning – the girl who got straight 9s, the boy who used to be badly behaved but did brilliantly, the disbelief of another pupil as he read, and reread, his results – “Miss, these can’t be real” – the staff celebration.

In a subsequent interview with the Guardian, Birbalsingh could not disguise her delight. “It’s really great. When you think all of our kids are from the inner city, they are from challenging backgrounds, they are deprived kids. I don’t have any white, middle-class kids in the school.”

Birbalsingh first attracted controversy when, as deputy head at a school in south London, she criticised school behaviour policies in a high-profile speech to the Conservative party conference in 2010. The speech alienated many in the teaching profession and she was left shaken and jobless.

It has been a long haul since then. Another tweet described her journey:

1. Told you will never work in the state sector again.



2. 3 years fighting detractors to set up a free school, call it Michaela.



3. 5 years with an amazing team, transforming kids’ lives & fighting the good fight every day!



4. Thursday August 22: GCSE results finally here 🥳 pic.twitter.com/u2DecBt6UN — Katharine Birbalsingh (@Miss_Snuffy) August 21, 2019

Ever since it opened in a converted office block close to Wembley football stadium in September 2014, Michaela has been the subject of intense scrutiny and debate, particularly over its tough behaviour policy.

Pupils are given demerits or detention for forgetting to bring a pencil or pen, or for talking in corridors when moving between lessons. The school hit the headlines again when it was reported that children whose parents had failed to pay for their lunches were made to eat separately from their classmates.

“I think it’s hilarious to say we are the strictest school in Britain,” laughed Birbalsingh. “It’s a joyful and happy place. The children are so happy to be here.” Two years ago, the schools’ watchdog Ofsted vindicated her approach when it judged Michaela outstanding in all categories. A second school, following the same model, has been approved and will open in Stevenage in Hertfordshire.

Birbalsingh puts Michaela’s success down to “conservative values – with a small c”. She lists them – belief in personal responsibility, respect for authority and a sense of duty towards others. “I’ve always known the school is great, because I’m here every day and the children are wonderful. What I’m most proud of is the young adults they’ve become. They are good people.”