Sir Bernard Hogan-Howe has paid tribute to Met Police officers and staff who have died while on duty, telling their families and friends "you do not remember and mourn alone".
Speaking during an annual memorial service held in their memory, the Met Commissioner said society was "forever in their debt" before joining Prince Harry, London Mayor Sadiq Khan and relatives of the fallen in laying wreaths and other floral tributes.
In the tranquil setting of a memorial garden at the Met's famous training centre in Hendon, North London, Sir Bernard told those gathered that 650 officers and staff had lost their lives in the line of duty during the Met's 187-year history.
He said: "I know there is much sadness here today. No-one can ever underestimate the pain that so many of you here today live with day-to-day, but I hope it will bring you some small comfort to know that you do not remember and mourn alone.
"You are all members of the Met family and we stand together and remember with you. I hope you do take great pride in the fact that your loved ones died in the job that they loved, serving the communities of London.
"We are forever in their debt."
Among the guests was Sid MacKay, 73, a former Chief Superintendent in the Met Police, whose daughter Pc Nina MacKay was fatally stabbed at the age of 25 on October 24 1997 by a paranoid schizophrenic during a raid in Stratford, east London.
Mr MacKay, who is the chairman of the Police Roll of Honour Trust, said: "You never expect to bury your child, that's the most hurtful part.
"People talk about closure ... I understand them using that term. For me, all closure means is the perpetrator's been caught, been dealt with. There's no closure, there's an aftermath which continues and will carry on."
The Commissioner described to the guests the circumstances that led to the death of the most recent officer: "On November 27 last year, PC Sahib Lalli was suddenly taken ill in Trafalgar Square after a night shift and taken to hospital where sadly he later died.
"He was only 38 years old. Sahib and his wife were expecting the arrival of their first child only one month later."
The Met Commissioner said 2016 was a year of "tragic anniversaries" and highlighted how 23 years to the day Pc Patrick Dunne was shot dead when he confronted suspects while investigating the sound of gunfire in Clapham, south London.
It is 50 years since Detective Sergeant Christopher Head, Detective Constable David Wombwell and Pc Geoffrey Fox were fatally shot when they stopped three occupants of a car in Shepherd's Bush, west London, in August 1966.
And he told the families how it was 100 years since the death of Detective Sergeant Matthew McLoughlin - the only protection officer to be killed on duty.
At the time of his death he was serving with Lord Kitchener in France but had been a protection officer to King Edward VII and George V.
During the ceremony, Prince Harry read the poem Do Not Stand At My Grave And Weep by Mary Elizabeth Frye and met the families and friends that came forward to lay a floral tribute.
He also planted a tree in the memorial garden.
Mr Khan also spoke during the ceremony and said: "Today is about paying tribute to those men and women who have paid the ultimate sacrifice in the line of duty. We will always be indebted to them and they will not be forgotten."