Christina Sinclair, the acting director of retail at the Financial Conduct Authority (FCA), is to leave the regulator and join Barclays.
Sinclair, who led the FCA crusade over payment protection insurance (PPI) mis-selling, is to aid clean-up at Barclays, according to Sky News.
She is to become the global head of compliance for wealth and investment management at Barclays.
Her appointment will reunite her with Sir Hector Sants, who joined Barclays last year as part of efforts by Antony Jenkins, the bank's chief executive, to repair its reputation following its £290m fine for its role in the Libor rate-rigging scandal.
Sinclair's move also marks the latest example of a senior regulator crossing the divide into the private sector, where roles of equivalent seniority tend to be significantly better paid.
She has spent 18 years at the City regulator in its various guises during that period, and played a leading role in campaigns to provide redress for the mis-selling of PPI and interest rate hedging products.
Those two scandals have cost the major UK banks well over £12bn, and Barclays has been responsible for more than £2bn of that sum on its own.
In an announcement about Sinclair's departure circulated among FCA staff and seen by Sky News, Clive Adamson, the regulator's director of supervision, said: "Christina made a substantial contribution on some of our flagship projects, including Payment Protection Insurance and Interest Rate Hedging Products, helping to secure billions of pounds of redress for consumers.
"Christina will be missed, but I am very pleased about her new role and know she will be a strong advocate for promoting the conduct agenda."
Ms Sinclair, who will join Barclays in October, is being replaced at the FCA by Andrew Giles, currently a special adviser in its supervision team.
In addition to its role in the Libor affair, Barclays is facing a string of awkward regulatory probes including one led by the Serious Fraud Office into the deal which saw it raise billions of pounds from Middle Eastern shareholders during the banking crisis.
A Barclays spokesman confirmed Ms Sinclair's appointment.
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