His list of concerns are understood to include the absence of a code of conduct - at a time when the AOC was exhorting member colleges to produce them - and the lack of a proper register of interests of the entire board.

John Hall, a senior partner of Britain’s second biggest law firm Eversheds, played a key role in the shaping of the rules of probity in FE under Lord Nolan’s committee of inquiry into standards in public life.

He resigned from the AOC in April and news of the circumstances surrounding his departure have sent shockwaves through the sector. One principal of an AOC college said: “I have every sympathy for Roger and feel that he was just perhaps a little unwise in his dealings.

“But the loss of John Hall, I find stunning.”

Mr Hall refused to comment to The TES beyond issuing a formal statement, at the request of senior Eversheds partners, through a PR agency used by the company.

It said that he had twice written requesting a meeting with the chair of the board, Howard Phelps, but had received no response.

In response to inquiries from Private Eye, a spokeswoman said Mr Hall was concerned about the lack of clarity of his role and issues such as “the endorsement of suppliers to the further education sector”.

However, sources close to Mr Hall and the Colleges Employers Forum - the employers’ organisation that preceded the AOC - told The TES he was concerned about the shareholdings in the part-time staff recruitment agency ELS and other companies dealing with the AOC.

The principal of an AOC-member college said: “Roger talks now about being up-front from the start in promoting ELS as the preferred agency for part-time staff in FE. My recollection was that there should be proper competition to ensure value for money.”