When Lewis Lesley was sacked for "gross misconduct" after 25 years' service at Liverpool John Moores University in 2003, it caused an outcry.
Lecturers' union Natfhe described the dismissal as "grotesque and contrived". The transport professor's colleagues signed a letter supporting him against a charge that he was "impossible to work with".
While the university has maintained that a review found no evidence of abuse in the handling of Professor Lesley's sacking, in the summer of 2003 he received a five-figure sum, thought to be close to £100,000, in settlement of a claim for unfair dismissal. He was also recommended for an emeritus professorship. This seemed to end the matter.
Until now that is. An investigation by The Times Higher has uncovered evidence that raises fresh questions about Professor Lesley's dismissal.
It also prompts renewed questions about the extent to which a university should protect the freedom of academics to voice controversial opinions - particularly when those views concern another public body with links to the university and these issues are muddied by long-standing vested interests.
It has emerged that several months before he chaired Professor Lesley's controversial disciplinary hearing, Michael Brown, LJMU's vice-chancellor, entered into correspondence with local public transport consortium, Merseytravel, about some of the professor's public statements.
Merseytravel was unhappy about criticisms Professor Lesley had made in the local press about its conduct during a long-standing row over rival transport schemes. The firm claimed these went beyond legitimate criticism and were defamatory.
The letters were never disclosed at the time of Professor Lesley's hearing.
But they reveal that Professor Brown told Merseytravel that he hoped the professor's actions would not "disturb the positive relationship" between LJMU and Merseytravel.
He added that Professor Lesley may wish to "consider his position" after being reminded not to express views in his capacity as a professor or on behalf of the university.
Natfhe this week demanded a full independent inquiry into the matter and said there should be a thorough examination of governance at the university.
But a spokesman for the university said there was no evidence to support Natfhe's allegations of abuse in the disciplinary process. He said: "The allegations relating to the disciplinary procedure have been thoroughly investigated by LJMU's employment committee, on behalf of the university's board of governors."
Adrian Jones, Natfhe official for the North of England, said: "The revelation of this correspondence throws this affair into a new light. Not only is the vice-chancellor's impartiality over Professor Lesley's dismissal now in question, but the principle of academic freedom is in shreds."
Natfhe said that Professor Brown should have disclosed the potentially compromising correspondence at the time of the hearing, so there could be no suggestion of any conflict of interest.
Mr Jones said that Professor Lesley might not have signed a compromise agreement giving up his right to reinstatement had he been aware of the correspondence.
Professor Lesley and Merseytravel had been long-standing adversaries beyond the usual relationship between an academic expert and a local organisation working in his field.
As head of Liverpool Electric Tram Systems, Professor Lesley had been promoting a tram system for the region since 1994. Merseytravel, a one-time supporter of the venture, pulled out in 1996 and the relationship turned sour. The acrimony was then often played out in the local press.
Merseytravel this week confirmed that its chief executive, Neil Scales, wrote to the vice- chancellor about Professor Lesley in 2002 to complain about "defamatory comments by (Professor) Lesley which appeared in the press".
A spokesman said the organisation had been concerned that Professor Lesley had wrongly "inferred" (sic) in the press that it had plagiarised his ideas for a Merseyside tram system, and that he "has also publicly stated on several occasions that Merseytravel had been instrumental in ensuring his (own) tram scheme would not succeed in obtaining planning permission".
"Both statements were untrue and, as Mr Lesley was at that time professor of transport science at LJMU and made his statements in this capacity, LJMU was warned it could be joined in any legal action if such statements were repeated," said Merseytravel's spokesman.
The company acknowledged that no legal action was taken beyond the initial threats - as the comments "were not repeated".
Merseytravel also confirmed that Professor Lesley had shown the firm in advance of publication a copy of one opinion piece he had written for a local paper, asking for comments.
But the company said: "It was returned unread with an explanation that it was not Merseytravel's job to proof-read articles for (Professor) Lesley and that he knew perfectly well the issues on which we disagreed, as these had been pointed out to him on several occasions."
Natfhe insists that the vice-chancellor should have stood up for the professor's right to raise criticisms about the conduct of a local democratic organisation.
Instead, in his reply to Merseytravel, Professor Brown said that should it wish to take legal action against Professor Lesley, he would receive no support "in any way" from the university.
Mr Jones said: "It is a fundamental principle that academics in a free society are entitled to express unpopular and challenging opinions without fear of detriment."
"University professors must be allowed to raise questions about how democratically accountable public bodies use taxpayers' money and conduct themselves. Every university's senior managers have a duty of care to protect that freedom."
An LJMU spokeswoman said the university would not discuss details of any disciplinary case outside the formal structures, as it could be harmful to the participants and also "holds the potential for unbalanced or incomplete versions of events to be portrayed".
She said: "LJMU has developed employment policies that reflect the university's fundamental belief that all staff should be treated with fairness, courtesy, dignity and respect."
A Merseytravel spokesman said that the company "was in no way responsible for, or party to, the dismissal of (Professor) Lesley". He said that any suggestion to the contrary would result in legal action for defamation.