Prosecutors have said there is insufficient evidence to suggest the officer who claimed Andrew Mitchell called him a pleb was lying as they announced one charge of misconduct against another constable over the affair.

Alison Saunders, the director of public prosecutions, said neither was there sufficient evidence "to show that Mitchell was the victim of a conspiracy of misinformation".

Saunders said one officer was to be charged with misconduct in public office. The officer, PC Keith Wallis, 53, allegedly sent an email to the deputy chief whip purporting to be a member of the public who had witnessed the incident.

The Metropolitan police said following the CPS decision five officers would now face gross misconduct panels – where the ultimate sanction is dismissal – a decision supported by the police watchdog, which was supervising the police investigation.

A further two officers will be dealt with by their superior officers in a locally managed misconduct hearing for providing inaccurate statements or inappropriate comments and an eighth officer will be spoken to by his managers in relation to inappropriate comments.

The four officers who face misconduct are accused of discreditable conduct relating to honesty and integrity and/or to the improper disclosure of information.

Bernard Hogan-Howe, the Met commissioner, said no action would be taken against PC Toby Rowland, the officer on duty in Downing Street who was involved in the altercation with Mitchell and who said he had been called a pleb, after the CPS concluded there was insufficient evidence to suggest he was lying.

Rowland's handwritten notes of the encounter, plus records of a conversation he held with his superior immediately afterwards, were examined by the police and the CPS as part of the inquiry. He has never been arrested.

Saunders revealed that in coming to their decision not to charge the majority of the eight individuals arrested – five officers and three civilians – prosecutors had viewed a vast amount of CCTV footage which has not been seen in public before.

She said: "Much of the press reporting to date has assumed that the CCTV recordings show that the gate officer lied about the words used during the incident." But she said the edited footage that has been aired by the Channel 4 Dispatches programme "did not show the full picture" [see footnote].

Saunders said: "It is clear from the footage that there was sufficient time for the words to have been said either as described by the gate officer or as described by Mr Mitchell …

"It does show there are a small number of members of the public present immediately in front of the gate … this is consistent with the officers' account that several members of the public were present … No officer ever mentioned 'crowds' being present – this was first mentioned in Channel 4 News/Dispatches programmes."

Saunders said there was insufficient evidence to prove that one officer alone or with other officers had fabricated a false allegation against Mitchell, and there was insufficient evidence to prove a criminal conspiracy against him.

On the leaks to the media of the original altercation, which was passed to the Sun, and of an email describing what happened, which has become known as the official log, which was given to the Daily Telegraph, she said that because there was no evidence of payment a jury was likely to decide that it was in the public interest for the events at the Downing Street gate to be made public. Therefore no officer would be charged over the leaks.

Wallis is currently suspended from duty and will attend magistrates court on 16 December.

In making their decision, Saunders said prosecutors had examined mobile phone records, emails, text messages, social messaging and telephone contact between numerous police officers and members of the public as well as the previously unseen CCTV footage.

Mitchell lost his job as chief whip over the altercation in Downing Street and has been fighting to clear his name ever since.

The CPS announcement comes after a year-long investigation, which has been closely observed and commented on by politicians from all sides of the political spectrum, many of whom have publicly come to the defence of Mitchell.

The altercation in Downing Street on 19 September last year took place after two police officers on duty refused to let him ride his bicycle through the gates.

In an incident that was partly captured on CCTV, the police log said Mitchell called them "fucking plebs". He has always denied using the word pleb but has admitted swearing.

Details of the incident – which took place the day after two female police officers were killed in a gun and grenade attack in Manchester – were leaked to the Sun the following day. The official log of the altercation, which appeared to contradict Mitchell's denial of using the word, was later leaked to the Daily Telegraph.

Over the last 14 months the police investigation has led to the arrest of five officers and three civilians.

The investigation, codenamed Operation Alice, was led by deputy assistant commissioner Pat Gallan. It involved detectives taking statements from all 800 officers who were or had recently been in the diplomatic protection squad.

• This footnote was added on 27 November 2013. The Crown Prosecution Service has since clarified that it has not maintained that the footage was edited by the Channel 4 production team itself.