She is head of Queen's Park primary, in Westminster, where 85 per cent of pupils speak English as a second language. In line with national trends, the school's scores in writing rose from 63 per cent at level 4 or above in 2005 to 85 per cent this year.
Ms Mayne attributes this to the task, which involved an imaginary lizard.
"The task was non-fiction creative writing," she said. "Reluctant readers and writers will respond favourably to non-fiction. This year's was a nice task, which helps. It was much better for boys because it had a lizard in it."
National results in maths dropped slightly this year. At Queen's Park, the percentage achieving level 4 or above fell from 81.4 per cent last year to 61 per cent this summer - much lower than the target of 70 per cent.
"I felt the maths paper was far more wordy than in previous years," Ms Mayne said.
"That meant children had to try to understand the questions, which took longer than the time allocated. Lots didn't finish the paper. Also, it seems easier to get level 4 in English than in maths. The bar is lower."
But she said she would query some marks. "It looks like people were marking papers while watching EastEnders," she said.
Ayoub Ahmed, 11, was pleased with his level 4 grade in the writing paper.
"I like lizards," he said. "It's boys' stuff. They've got mud and stuff on them, so I was happy to write about lizards in the test."