A Cardiff teacher nicknamed “the maths whisperer” after his entire class of 30 pupils gained an A* at GCSE was back in school on Wednesday, with hopes high for the summer exam season.

Francis Elive achieved celebrity status this week after every one of his year 11 pupils at Fitzalan high school received top marks, even after sitting the exam six months early.

Fitzalan’s top-scoring pupils have all been taught by Elive since the start of secondary school. Many of them achieved almost full marks in the test, which is set by the WJEC exam board.

In an interview with Wales Online, Fitzalan’s assistant headteacher, Jo Kemp, paid tribute to Elive and his students. “We did a countdown so they all opened their results at the same time. There was a gasp as they saw their results and then all realised they had the same.”

She said Elive, who has taught at the school since 1997, was passionate about his subject. “He is quite a reserved man but he was just on pins like an expectant dad – how you would want a teacher of your children to be feeling.

“We call him the maths whisperer. He instils the belief that they have practised the hardest maths that they have to ever face, so why be scared of an exam? It’s the belief that they absolutely can do it, and the children think it’s magic.”

The highly rated state secondary serves a catchment area where there are high levels of social and economic disadvantage and approximately 70% of pupils come from a minority ethnic background and speak English as an additional language, according to the Welsh schools’ inspectorate, Estyn.

In Wales, GCSEs are still graded A* to G, unlike in England where they are graded 9-1. The Fitzalan result is all the more remarkable as only 13% of pupils who sat the exam in Wales last summer achieved an A or above.

Cllr Sarah Merry, the cabinet member for education, employment and skills at Cardiff council, welcomed the school’s success.

“What an incredible result. I don’t think I’ve ever heard of an entire class scoring A* across the board,” she said. “I want to congratulate all the pupils, their teacher Mr Elive, and of course the school for this wonderful achievement.”