Text messages provided to the Sunday newspaper indicate that Paul Flowers was involved with hard drugs in the days surrounding his appearance (right) before the Treasury Select Committee on November 6 about the Co-op Bank’s disastrous performance.

Mr Flowers has been widely criticised for his performance in front of MPs as he told the committee the Co-op’s balance sheets had £3bn of assets, when it was actually £47bn.

And he admitted that his financial qualifications amounted to a four-year stint in a bank after leaving school, more than 40 years ago, adding: “I would judge that experience is out of date in terms of needs of contemporary banking."

Committee chairman Andrew Tyrie said of Mr Flowers’ testimony: “We were provided with further evidence that the chairman of a bank must have a good deal of financial expertise."

Mr Flowers was asked to stand down from the Co-op bank by new group chief executive Euan Sutherland in May, after the £1.5bn shortfall was detected. He was replaced by Richard Pym, former head of Bingley-based UK Asset Resolution.