A former head of one of the UK’s biggest unions has challenged one of the key findings of an independent report that said the organisation was “institutionally sexist”. Sir Paul Kenny, general secretary of GMB between 2005 and 2015, said Karon Monaghan’s inquiry had unfairly criticised his actions after he had suggested giving a £30,000 payoff to a member of staff under investigation for gross misconduct. His comments, which question a conclusion of one of the UK’s foremost experts in equality and human rights law, will reignite a battle within the union over the treatment of women. Monaghan was appointed this year to conduct an independent inquiry after the sudden resignation of Tim Roache as general secretary amid allegations of misconduct, which he has denied. In a report released on Wednesday, Monaghan wrote that “a senior man within GMB intervened in an investigation process into ‘a serious incident of sexual harassment’”. The senior man wrote to the union’s human resources section and suggested that the accused, who was a male staff member, should be relocated to a new job and given a £30,000 payoff. “Such a course of action would remove the need for the women who lodged the complaint to be cross-examined,” the senior man wrote. Monaghan concluded: “There was no reasonable basis for bringing an end to the disciplinary process, or for that person to intervene in the process at all. I am satisfied that the interference in the process was wholly inappropriate.” Speaking to the Guardian, Kenny acknowledged that he was the senior man identified in the report and that he had been interviewed by Monaghan, but claimed she could not reach a fair conclusion because she had not spoken to the accuser and the accused. “That is an opinion based on a lack of knowledge. They never had the file, they never interviewed the people concerned, that is a judgment that someone might make who had no knowledge of the incident or of the evidence. None at all,” he said. “She may well be a barrister, but that doesn’t mean she is a brain surgeon. You make assumptions without interviewing the various people concerned.” Kenny said he had personally interviewed both the accused member of staff and the accuser soon after the alleged incident, and questioned Monaghan’s statement in the report stating that there had been a serious incident of sexual harassment. “It is just not true. It just wasn’t the case and is not played out by any of the facts at all. The police were called and decided not to pursue the case.” Kenny said the accused man had not received any payoff and had left the union with his notice and holiday pay. “I didn’t do anything underhand. I put all my actions on record,” he said. Monaghan made a list of 27 recommendations to the union, including taking steps to increase the representation of women at all levels and introducing a bespoke complaints procedure for sexual harassment and an annual equalities audit. The report concludes that sexual harassment is common in the union, which has more than 600,000 members. A GMB spokesperson said the union stood fully behind the report. “Karon Monaghan QC is an eminently respected lawyer and an A-panel member of the Equality and Human Rights Commission panel of preferred counsel. “GMB fully accepts her report and its findings, and we’re committed to the fundamental change that is needed to take the union forward. Misogyny will not be tolerated in any form. We fully stand by the integrity and thoroughness of her investigation.” Monaghan declined to comment.