Should the poet Derek Walcott ever be rehabilitated into academic society? Only a few weeks ago, it appeared that time, talent, seniority and the Nobel Prize for literature may, finally, have earned him the further honour of a clean slate.

Over a quarter of a century since he admitted to propositioning a Harvard student, authorities at the University of Oxford clearly consider the poet harmless to the young. They made no objection when Walcott, who was born in the same year as the late Ted Hughes, was nominated to be its next professor of poetry. This chair requires the incumbent to deliver three public lectures per year. Walcott instantly became the favourite. Yesterday, the closer of his two rivals, the English poet Ruth Padel won the job instead.

Why? Evidently Ms Padel, with her professed commitment to "thinking out of the box", has her fans. Others will be aware that she is a direct descendant of Charles Darwin, the subject of a good many of her poems. But we cannot know how many Oxford voters preferred Padel's work to Walcott's because last week, after anonymously circulated attacks on his character, the older poet withdrew from the contest. "If it has degenerated into a low and degrading attempt at character assassination," he explained, "I do not want to be part of it."

For her part, Padel pointed out that the nasty personal attack on the more distinguished candidate could not properly be described as "a smear". "The papers they sent out," she stressed more than once, "were published fact."

By "they", Padel means the senders of photocopied extracts from a book about sexual harassment called, presumably because Nancy Mitford had already bagged its natural title, The Lecherous Professor. Several pages are devoted to a Harvard student's description of Walcott's misconduct. This occurred one November evening in 1981 and features various cringe-making declarations of sexual interest.

When the incident was investigated, Walcott endorsed this version of events, but never repented. Nor did he apologise for his subsequent award of a C grade to the student's poems, which was later raised to a pass by Harvard, presumably recognising her claim to have been vengefully marked down.

Perhaps it is this disdainful absence of remorse that enrages Walcott's critics, to the point that they still fixate on a misdemeanour that predates war in the Falklands and are now to be found exulting, on various online communities, over his humiliation.

Of course, with the semi-exoneration of Ted Hughes which followed posthumous publication of his collected letters, a vacancy has arisen for a male poet whose name, like his and Philip Larkin's, serves as a target for unhinged, supposedly feminist loathing. John Walsh, of the Independent newspaper, was the first to cast doubt on "creepy" Walcott's credentials, compared with those of Ruth Padel, whom he describes as "my old friend".

The Harvard business was not one-off, he disclosed: "Should one not mention Ms Nicole Niemi, 30 years his junior?" This student had come forward in 1995, Walsh said, "to claim that when she was a creative writing student in the 1980s, Walcott threatened to fail her unless she went to bed with him".

Yes, one should certainly mention Ms Niemi. After making the accusations to which Walsh refers, she settled with Walcott out of court, without comment on either side. And now Ms Niemi has come forward again, under her married name, Nicole Kelby. "I am appalled and saddened by the anonymous smear campaign against my former mentor, Derek Walcott," she wrote last week.

Her intervention came too late, unfortunately, to prevent Mr Walcott quitting a contest the university might have done well to abandon, given the disinclination of the two remaining nominees to withdraw in disgust. Apart from anything, a restaged election would have attracted poets who had been deterred, before, by Walcott's pre-eminence.

But Ms Kelby's statement at least stands as a rebuke to Walcott's more sanctimonious persecutors, with their conviction that the sexual attitudes for which he was arraigned almost three decades ago should never be forgiven. Although Walcott's supporters have been zealous with reminders that Byron was no saint, and that brilliant writers can be the baddest people, the most persuasive defence, in his case, is surely that his level of misbehaviour was once, allowing for the shortage of women students, commonplace. Even the American authors of The Lecherous Professor, in which the account of Walcott's infamy takes pride of place, acknowledge that victory over student-molesters occurs late in the annals of feminist achievement. "As late as 1974," they report, "there was still no general consensus about sexual harassment."

Perhaps the speed with which sex with students has become a literary theme, courtesy of Roth, Mamet, Franzen, Coetzee and others, has led to the impression that universities have always advertised the transgressive aspect of these relationships. But in 1982, at the time of the Walcott complaint, Harvard's procedure for dealing with harassment claims was secretive and rudimentary. "As long as Harvard promises that mum is the word on cases of sexual harassment," wrote a contributor to the university's newspaper, that year, "open season will remain on women undergraduates."

In Oxford, at around that time, such asymmetrical - as they are now called - relationships were similarly unregulated. Sometimes, one heard, they were of an exciting, Roth-like nature; sometimes they were not. When one tutor found a pretext to come to my room, where he backed me against a wall and forced his flobbly tongue into my mouth, it seemed simplest, as a teenager in the Seventies, to change course. How did one report to a non-existent authority a nameless offence against a code which did not yet exist? Looking back, although I cannot feel warmly about the beardy little git, I think he was no less evolved for his time and place than many.

Mercifully for our daughters, Beardy's successors have moved on. Or at least: no university teacher, no matter how much he might resent them, can be ignorant of the penalties for sexual harassment. One can only deplore the relative backwardness in, to name just one profession, the political field. Here, quondam molesters such as Bill Clinton and John Prescott still prosper without, for instance, John Walsh, reminding them of unsuitable liaisons documented a lot more recently than 1982.

Agreed: outside the terrifying world of poetry, the rights and wrongs of this obscure election don't amount to much. Who cares if Oxford has, in giving way to malevolent smears, ended up with a mediocre versifier, exchanging, in the process, its first black poetry professor for the first woman one?

It's only five years until the next election. In the light of Walcott's lifelong ban, interested poets may want to start reviewing their personal history for any episodes that a younger and more enlightened person may find, with the best will in the world, creepy.