By Dominic Casciani
BBC News home affairs reporter
What are the police for? They're there to deal with crime - that goes without saying. But has the office of constable morphed into something far more complex and challenging over the last few decades?
That's the question at the heart of an MPs' report into the future of policing, and it is a question that some police representatives are also asking themselves.
According to MPs on the Home Affairs select committee, police are facing the "challenge of a gradual yet significant expansion" of responsibilities.
At the heart of this debate is the difference between duties which are "mission critical" - the core of the job - and "mission creep" - duties that have been added on.
At their heart, Sir Robert Peel's guiding principles of policing set out in the 1820s have remained fairly unchanged: uphold the law, prevent crime and bring offenders to justice.
But society has been changing, and so have the police.
We didn't have radios or any communication other than the police call boxes and the police posts, which were just a phone with a flashing light if you were required
For example: the police have traditionally been charged with protecting the neighbourhood. It's a local job, which is focused on local results, and provides local reassurance.
But where do the not-so-obvious offences fit in?
These are crimes that are more difficult to spot, such as internet-driven child abuse, the financing of terrorism and complex frauds.
Most people would agree that even though tackling these extra offences would not have been a job for a 19th century police officer, it is still vital that modern police take on these "mission critical" duties.
But it is the "mission creep" jobs that are proving more controversial.
The Liberal Democrats have accused Labour of creating some 3,600 new offences while in office.
Meanwhile, the Home Office has set out specific targets that each constabulary needs to reach.
And on top of all this, a drive towards "joined-up thinking" in government means police forces around the country have broader responsibilities with other local authorities to tackle particular problems.
'Lack of clarity'
The Association of Chief Police Officers told MPs that the modern police service had a mission that is wider than ever before - but there is a lack of "shared clarity" about what was expected of it.
Chief Superintendant Steve Dunn, a borough commander in East London, told MPs: "What are we there for? I think we need some clarity around that. Why do we take lost property? Why do we take lost dogs? Is that what we should be doing?
POLICING REFORM PROPOSALS
Cut red tape
New policing pledge
Standards for time on the beat
Source: Home Office Policing Green Paper
"We need to fundamentally review what policing is about.
"You have some people saying, 'enforcement'. Other people are saying we should be in prevention, education. It is such a complex business now."
This tricky problem becomes more apparent when you look at public confidence in police to get the job done.
After many years of officers fighting crime from inside their patrol cars, the police have now gone back on the beat and reverted to a neighbourhood model.
This means that, in theory, they and the newly-created community support officers are spending more time on local crime.
However, bringing the police back into contact with the people they serve has had only a limited effect on public satisfaction.
Home Office figures show only only 53% of people think the police are doing an excellent or good job - and only four out of 10 people said officers could be relied on to deal with minor local crimes.
So while priorities have changed to focus on the neighbourhood, it appears that many people don't think that has gone far enough.
Part of this public disillusionment can be attributed to an apparent rise in police red-tape.
The Home Office says that in 2007, 13.8% of time was spent on patrol and 64% on "frontline duties".
But the official definition of "frontline" duties is itself controversial.
MPs say that these duties includes working on case files back in the station - rather than being out on the beat which is where most people might place the "frontline".
The coming years may see some rapid change. The Home Office's 2008 policing green paper proposes cuts in red tape, national standards for beat time, easier ways to contact officers and greater local accountability.
Paul McKeever, chairman of the Police Federation which represents rank-and-file officers, says the Home Office should learn from the MP's findings.
"The report emphasises that some minor steps have been taken, including the shorter stop and account form and the scrapping of plans to civilianise the custody sergeant. Both moves were welcomed by the Federation.
"The service needs clarity, direction and leadership. We hope that the content of this detailed and thorough report is used by the Home Office to deliver a wider base for review and reform than recently attempted in the Policing Green Paper"
The Home Office has ended its consultation on the proposals. The final proposals next year may help answer what the police are for.