The Whitehall investigation into Tory MP Mark Field, who was suspended from his Foreign Office job after manhandling a female protester at a black tie event, has been dropped, No.10 has announced. 

Downing Street said on Monday that Boris Johnson considered the issue was “a matter for the previous prime minister concerning his conduct during his time as a minister under her appointment”.

City of London Police also dropped its investigation into Field.

But Labour said today Johnson should expel Field from the party.

Field triggered a fierce backlash in June after he was filmed grabbing climate change activist Janet Barker by the neck as then Chancellor Philip Hammond was speaking to a black-tie event in central-London.

Theresa May suspend him from his job as a Foreign Office minister after viewing footage of the incident which she found “very concerning”.

Field referred himself to the Cabinet Office for investigation and has apologised “unreservedly” to the activist.

At the time, Barker said she had expected resistance “but not to the extent which I received”.

“I expected to maybe engage in a conversation or two with people, perhaps people blocking my way. But certainly not to be grabbed round the neck,” she told the BBC.

Asked what she thought of his actions, she said: “They were pretty much over the top.

“We were peaceful, I was simply walking past his chair – or trying to walk past his chair. They were really over the top.” 

A City of London Police spokesperson said: “Following the incident at Mansion House on June 20 when trespassers disrupted the annual Bankers and Merchants dinner, we received a number of reports that an offence of assault had occurred.

“Following careful assessment and giving consideration to the events of that evening and the subsequent views of Janet Barker in relation to the action of Mark Field MP, City of London Police will be taking no further action against Mr Field.” 

“Never mind not being fit for a job in government, Mark Field isn’t fit to be an MP.

Louise Haigh, Labour’s shadow police minister, said it was “not good enough” for the PM to consider the matter closed. 

“Having previously failed to condemn his actions, this is a test of Boris Johnson’s attitude towards women. He should kick him out of the Conservative party immediately,” she said.