Last Thursday, Sadiq Khan announced that from April next year there will be 400 more firearms officers in London. ‘Nothing is more important than keeping London safe,’ the mayor said in his first major announcement concerning the capital’s policing. The Metropolitan Police commissioner, Sir Bernard Hogan-Howe, had asked for more armed police after last November’s terror attacks in Paris. On 1 April, Downing Street announced that £143 million would be spent on ‘increasing the number of specially trained armed officers’. But senior figures in the police are telling the BBC that still isn’t enough.

The mayor’s office claims that more armed police in London would better ‘protect the capital from gun crime and terrorism’. But it was in the name of protecting London from gun crime and terrorism that Jermaine Baker, Mark Duggan and Jean Charles de Menezes were killed.

Baker, a young black man, was shot by the police in a car near Wood Green crown court last December. They suspected him of being about to try to spring two prisoners from a police van. His alleged co-conspirators are currently on trial. Last week, the jury heard evidence that the weapon recovered from the car was a replica, found on the floor of the back seat. Baker, sitting in the front, was shot through the windscreen. The IPCC arrested one of the officers involved in the operation (they’ve investigated 29 fatal shootings by police in the past 12 years; this is the only arrest they’ve made). The officer’s colleagues responded by threatening to step down from duty.

The operation that killed Duggan, another young black man, was designed to take a gun off the streets, but instead took a life. The inquest into his death found that when V53 (an unidentified firearms officer) fired at him, Duggan was unarmed. Somehow the jury still found that his killing was lawful, but many people in Tottenham don’t accept that.

Jean Charles de Menezes died at Stockwell Tube Station two weeks after the 7 July 2005 bombings. Specialist officers, with authorisation from the very top of the Met, fired eight shots into the 27-year-old Brazilian electrician’s head and torso in the unfounded belief that he was a terrorist. No individual officers were ever held responsible for the deadly mistake.

There seems to be no plan for increasing accountability among the officers most capable of deadly force. On the contrary, firearms officers complain that they are already too accountable. ‘What they are worried about,’ according to Simon Chesterman, the National Police Chiefs’ Council lead expert on armed policing, ‘in the event they have to use lethal force, is that they make a split-second decision and are pulled apart for up to 10 years.’

The Home Office says that ‘it is for operationally independent chief officers to determine the number of authorised firearms officers in their areas based on a thorough assessment of threat and risk.’ Khan’s rush to support Hogan-Howe’s new marksmen suggests little attention has been paid to the ‘threat and risk’ of more police carrying guns. In March, the home secretary opened a public inquiry into the death of Antony Grainger, an unarmed man shot dead by Greater Manchester police in 2012. Campaigners argue that as well as individual cases, the question of deaths from police shootings needs to be reviewed as a whole.

Read more in the London Review of Books

David Renton: The Killing of Blair Peach · 22 May 2014

Katrina Forrester: In Bed with the Police · 7 November 2013

Thomas Jones: Ian Blair and the IPCC · 6 April 2006

John Upton: Terror, Muslims and the Met · 22 January 2004