As one of Britain’s most senior financial regulators, Sir Andrew Large has usually been the one writing the rules and dishing out the punishment. So it was ironic that he inadvertently provided the “smoking gun” in one the most celebrated financial scandals of recent times: the public school price-fixing cartel.

It was a letter from the bursar of Winchester College to Sir Andrew, a former pupil and now chairman of the governors, that helped to alert monopolies regulators to the problem. Attached to details of planned fee rises at other schools, it read: “Confidential, please, so we can’t be accused of being in a cartel.”

That evidence helped to clinch the Office of Fair Trading case against most of Britain’s top independent schools.

It was a rare setback in a blemish-free career for Sir Andrew, who as chairman of the Securities and Investments Board in the 1990s did much of the spadework for modern-day City regulation.

During his time there, he helped to reduce the abundance of regulators from five to three and spearheaded the crackdown on pensions mis-selling.

After the SIB, Sir Andrew became deputy chairman of Barclays, alongside fellow Wykehamist Andrew Buxton. At Barclays, he played a role in the ousting of chief executive Martin Taylor, but was himself later sidelined by the bank’s executive directors, his job becoming more part-time.

After a spell in Brussels, modernising clearing and settlement across Europe as chairman of Euroclear, he was rewarded with deputy governorship of the Bank of England, with responsibility for financial stability from 2002 to 2006.

In what proved to be a prescient warning three years ago, he suggested that institutions should be focusing much more on liquidity issues, not just balance sheet strength.

The son of an army Major General, Sir Andrew developed a taste for globe-trotting early, taking a job in Malaysia with BP. He came to investment banking aged 29, working first at Orion Bank and then at Swiss Bank Corporation. A committed educationalist, Sir Andrew is also a director of the Paris-based business school Insead, which he attended, and a governor of Christ College, Brecon.