When Michael Birdsall’s first child was born he applied for a place on the MBA course at Cambridge Judge Business School. He thought fatherhood necessitated a stable career, perhaps in management consultancy, rather than the freelance home tutoring service he had been providing for the previous eight years.

But he changed his mind when, as part of a research project for Judge’s mandatory entrepreneurship class, Mr Birdsall discovered private English language tuition for Chinese children was a $50bn market. “I thought?.?.?.?this is really something,” he says.

Nine months later, in his final semester, Mr Birdsall launched Two Sigmas, an online education marketplace that now connects more than 50,000 English teachers from the UK, US and Australia with Chinese parents seeking one-on-one lessons for their offspring. Users pay $45 an hour for lessons, of which teachers receive about $25. Two Sigmas has been profitable for the past year, and Mr Birdsall is now developing a virtual classroom teaching service.