It seems a bit of a fudge. In a letter to Joanne McCartney (Chair of the Police and Crime Committee), Ed Williams (the GLA's Monitoring Officer) points out that all he can really do is work out whether what happened amounted to potential criminal conduct. Williams spoke to the City Hall employee and established that there was "contact" between the Deputy Mayor and the woman, though not necessarily in the way described in the media (a 'bottom pat' in a lift). Williams didn't talk to Greenhalgh to get his side, which seems a bit weird.
Under the restricted terms which he was operating, Williams concluded that the incident was not a "Conduct Matter", though noted that Greenhalgh has "fallen short of expectations". Any further admonishment or action has to come from the Mayor himself as Greenhalgh is his direct appointment rather than a GLA employee. Boris confirmed at this morning's Question Time that he will remind Greenhalgh – and all City Hall staff – that he takes "a very strong line on sexual harassment and discrimination". There will be no further action because Boris believes there's a "lack of clarity" about what happened, even though we have the clear word of the woman and a quick interview with Greenhalgh would surely provide a bit more "clarity".
Johnson was also at pains to point out that no formal complaint has been made by the woman, and that she's anxious for her name not to be dragged through the papers. Without a formal complaint the incident ends here. Though we're going to take a moment to note that perhaps any future victims of harassment will be put off if they don't think the person accused will even be questioned.