Dwindling budgets will force the police to be more selective about the duties they carry out according to Met Commissioner Sir Bernard Hogan-Howe.
In recent years the Met’s budget has been cut by £600m and is expected to fall by a further £800m by 2020.
Although the force is selling off surplus and under-used buildings to generate cash, it has still had to axe thousands of civilian staff leading to fears that the mix between frontline officers and support staff is no longer in balance.
Earlier this year the London Assembly warned that Mayor Boris Johnson’s pledge to keep officer numbers “at or around 32,000” risked hampering the force’s modernisation by imposing a high salary bill and limiting its scope to review how to best serve Londoners.
Last year Her Majesty’s Inspectorate of Constabulary warned the Met might need to reduce officer numbers in future years in order to meet the ongoing budget pressures.
Mr Johnson has previously rejected this suggestion, insisting there are a range of funding options open to his successor to maintain the frontline after 2016.
However, in a speech delivered on Thursday evening, Sir Bernard appeared to accept that the force’s headcount will fall and said it would in future have to say some things were beyond its resources.
Speaking at the Royal Society of Arts, Sir Bernard said: “If you had any doubt, if my officers had any doubt, then let’s be clear – the Met is a ‘can-do’ organisation, and I am a ‘can-do’ leader. A smaller Met can make London safer.”
“But we need to spell out, like the military has, that we can’t promise to tackle everything the world throws up within a shrinking budget. If we try to fight on all fronts, we’ll fail on some. If we’re not clear what’s beyond our reach, how can others take responsibility?”
Sir Bernard and other Met leaders have previously highlighted the burden placed on the force from detaining those with mental health issues and transporting others to hospital.
Around 40% of calls the Met responds to involves those with mental or other healthcare needs.
The Commissioner said it was now time to look at how other emergency services, the criminal justice system, and local government could work together to avoid over-stretching the force.
He also called for crime prevention to be embedded in Government and policing policy just as healthcare had shifted from treating disease to preventing it.