The arrest of a police constable over the alleged leaking of information surrounding the "plebgate" row has been criticised by rank-and-file officers' representatives.
Met Police Federation chair John Tully questioned whether it was proportionate as the fallout continued from the foul-mouthed outburst which forced Andrew Mitchell to quit the cabinet.
A Diplomatic Protection Squad officer was arrested on Saturday on suspicion of misconduct in public office. He has been suspended from duty and bailed to return in January.
As the case was referred to the Independent Police Complaints (IPCC) watchdog, Mr Mitchell renewed his claim that elements of a police log obtained by newspapers were "false".
The MP resigned in October after weeks of controversy over what he was reported to have said to police after being told he could not ride his bike through the main gates of Downing Street.
In his resignation letter, he admitted swearing at one of the officers on duty at the famous address - delivering as his parting shot: "I thought you guys were supposed to f****** help us." But he firmly denied directing the words "pleb" or "moron" at him.
The story of the set-to first emerged in The Sun and transcripts of what was allegedly said, including those insults, appeared later in the Daily Telegraph. Fresh information was obtained by the Metropolitan Police on Thursday about how the press came by the published information, leading to the arrest.
A Scotland Yard spokesman said there was "no evidence to suggest any of the officers involved in the incident were involved in the unauthorised release of information".
Mr Tully told the Daily Telegraph that lawyers may argue that the arrest was disproportionate under present guidelines and that the officer could have been interviewed under caution.
"The thing which disappointed me is around the proportionality of whether it was necessary to arrest the individual. After all, he is a serving police officer," he told the newspaper.