Ex-KPMG chief John Griffith-Jones - now head of City watchdog, the Financial Conduct Authority (FCA) - has found himself at the centre of a growing storm over the role of the auditor in the HBOS scandal.
The former KPMG UK chairman - who retired from the Big Four firm in August 2012 - is facing mounting calls to resign over the clean bill of health awarded to HBOS while KPMG was auditor.
It follows calls from UK shareholder advisory group Pirc calling for an independent probe into how KPMG audited HBOS in the run up to the bank's collapse, in a letter to the Financial Times on Wednesday.
An FCA spokeswoman said: 'John Griffith-Jones was subject to a rigorous appointment process by the Treasury, and had a pre-commencement hearing with the Treasury Select Committee, to assess his suitability for the role.
'John does not sit on the board sub-committee of the FCA which is tasked with overseeing the HBOS report. The report will also be examined by three independent reviewers, who were appointed by the Treasury Select Committee, to ensure that it is a true representation of the facts.
The FCA is not responsible for regulating auditors, which was the Financial Reporting Council's (FRC) responsibi.
'As part of our report into HBOS, we will look at the factual input of auditors in areas such as provisioning and will ask questions where appropriate,' she said. 'However, this is not the same as assessing whether an audit has been conducted correctly, which would be a matter for the FRC to examine'.
She added that Griffith-Jones had declared an interest on HBOS in the published minutes of the FSA's board meeting from September 2012.
The furore is the latest chapter in the collapsed bank's unfolding saga - after ex-HBOS chief executive, Sir James Crosby, this week asked to be stripped of his knighthood and cut a third off his £580,000-a-year pension over his role in the institution's collapse, which led to a £30bn taxpayer-funded bailout.
His dramatic move follows the criticism he received in a report from the Parliamentary Commission on Banking Standards, which described him as the 'architect of the strategy that set the course for disaster'.
Griffith-Jones was appointed to the FCA role in June 2012 and retired from KPMG two months later, having been at the firm since 1975.
The issue highlights concerns over the Big Four firms' old boy network, slammed in a 2012 report by the Competition Commission. It revealed how 60% of UK audit committee chairmen and 66% of CFOs had once worked for one of the four major accountancy firms.
Professor Andre Spicer, a lecturer in organisational behaviour at Cass Business School, said one of the reasons the Big Four take on so many juniors is to be able to plant them in client firms. He said their alumni networks organise reunions for year groups and industry sectors, allowing current staff to socialise with former employees.
A KPMG spokesman said: 'We stand by the quality of our audit work.'
HBOS's auditors KPMG agreed that the overall level of the firm's provisioning was acceptable. However, in relation to corporate, they consistently suggested that a more prudent approach would be to increase the level of provision by a significant amount.