A standards panel has ruled that Boris Johnson's failure to formally disclose his relationship with unpaid City Hall adviser Helen Macintyre prior to her appointment was an "oversight" and requires no censure of the London mayor.
The assessment subcommittee of the Greater London authority said the mayor had committed a "minor technical breach of the code of conduct" after failing to declare that he knew Macintyre and her then-partner Pierre Rolin on signing a mayoral direction relating to a project for the Olympic Park Visitor Attraction to which Rolin donated £80,000 and Macintyre was appointed in a voluntary fundraising role.
John Biggs, the deputy leader of the Labour group on the assembly, lodged a complaint last month alleging that "the mayor may have brought his office into disrepute by failing to declare a close personal relationship with two people", following media reports over the summer alleging that Johnson had a past friendship and affair with Macintyre.
Johnson, who vowed to end "cronyism" in City Hall after taking office in 2008, refused to be drawn about the allegations but insisted over the summer that Macintyre's appointment for the unpaid and "informal" role was the result of a "thorough, transparent process".
But, after questioning the mayor regarding the complaint, the assessment committee said Johnson had failed to fully understand the code governing his conduct, as opposed to deliberately seeking to conceal matters.
Allegations surfaced over the summer claiming that Macintyre, an art consultant, had an affair with Johnson that began in January 2009. The following month Johnson met Macintyre and her then-partner, Rolin, a Canadian property billionaire, at a conference in Switzerland where it is understood they had drinks together.
That May, Johnson signed a decision to approve a donation of £80,000 towards a 400ft tower project at the Olympic site.
The panel said in its decision that the mayor did not realise the definition in the code of conduct of "close associates", was wide-ranging and could mean "a friend, colleague, a business associate or someone whom the member knows through general social contacts", or anyone with whom he is "in regular or irregular contact over a period of time".
The decision notice stated: "The mayor acknowledged that a potential interest had not formally been disclosed at the time of signing a mayoral decision form and that he would bear in mind the definition of close associate for the future."
The Labour group is not expected to appeal against the decision.