British private schools have suffered greater falls in student numbers than previously reported and should not expect the situation to “magically reverse”, according to a new report.

Previously the recession had been blamed for inflicting losses largely on girls’ schools and establishments in the North and South West of England. But the National Independent Schools’ Benchmarking Survey has issued a stark warning that tough times are likely to continue: 2012-13 could be a “watershed year”, setting the trend for “the next few years”, it says.

The report, based on a survey of 555 schools, reveals drops in student numbers in types of school that until now had been holding out against the recession. The 0.6 per cent fall in student numbers in senior and all-through schools was the largest recorded in a single year for 17 years. And joint day and boarding schools lost 0.5 per cent of their students this academic year, suffering their first decline for the same period, according to the report.

“The effect of the recession on pupil numbers from September 2012 is wider and does not just affect certain sub-sectors,” the report states. “The reduction is spread very widely across most types and sizes of school and across most parts of the UK, even in those areas and school types which up till now have been largely immune from the effects of the downturn.”

Mixed establishments joined girls’ schools in experiencing a fall in students this year, although numbers at boys’ schools continued to climb. Regions including the Midlands, Scotland and the South East also suffered a decline in numbers.

The analysis, carried out by Tim Baines at accountancy firm Crowe Clark Whitehill, comes after the Independent Schools Council, which represents UK private schools, revealed that there had been an overall drop of 0.3 per cent in its schools’ student numbers this year, after a slight rise last year.