What will be the cost of cutting police officers and staff?
I've just been to a session at City Hall examining just that and what impact the Government's spending review due in October could have on the capital's police service.
London Assembly members were picking the brains of four experts.
There was much discussion about what Londoners currently expected i.e. bobbies on the beat and how to maintain confidence in policing in the face of challenging economic circumstances.
One of them was Dr Tim Brain, former Chief Constable of Gloucestershire.
After the meeting, he said the worst-case scenario would be the Met potentially losing up to 13,500 police officers and staff by 2015.
He was referring to a post emergency budget briefing by the well-respected, independent think tank, the Institute for Fiscal Studies.
But he stressed: "It is important to follow the logic through. The IFS in their briefing said that over four years the country would effectively go back to levels of public spending last seen in 1997-8."
"In 1998, the Met had 39,692 full time equivalent posts, both police officer and civilian. This compares to 52,934 now."
He believed that the full impact of the cuts in staffing would be felt after the London Olympics in two years' time.
Yet he then added there was "no certainty" that this is how it will work out."
He said the best case scenario would mean the loss of around 3,000 full-time posts, through a combination of a recruitment freeze and natural wastage.
"In any event, the number of officers will fall from next year. It will be difficult for the Met to convince the public that front line policing will be unaffected. However, we don't know yet whether the overall savings will be closer to 25 or 40 per cent. "
It will be difficult for the Met to convince the public that front line policing will be unaffected.
Staffing costs make up around 80 per cent of the police budget so it's unlikely Scotland Yard's top brass will escape an inevitable restructuring of the workforce.
That will mean the Met will shrink, most probably from support roles like admin and clerical staff.
This though would have a knock on effect because uniformed officers would then have to take up the slack and that would mean less time for them on the beat.
But the police authority chairman Kit Malthouse recently said: "It is not about headcount. It is about what police officers are doing with their time."
In other words, the Met has to think smart. Officers are already being told to patrol alone rather in pairs to increase the uniformed presence on the street.
Today, Bernard Hogan-Howe, former Chief Constable of Merseyside and currently Her Majesty's Inspector of Constabulary for the Met, said patrols would have to focus on where large numbers of people congregate including schools and railway stations.
He said it was important to patrol around schools where officers could build up a relationship with parents and children, and in turn increase confidence.
There are difficult times ahead. Your thoughts are welcome.