Asked who could have foreseen them he replied: “One would have to point to the government.”

It had failed to realise how important the public thought tough sentences were: “Sentencing is crucial to confidence. The government has underestimated how important sentencing is to public confidence.”

He said he was talking about offenders who commit burglary, car crime and violent street robberies, and not the most serious crimes of rape or murder.

Recorded crime has been falling for three years, and latest figures show a 12% year-on-year fall, but the prison population is up from 61,000 in 1997 to 83,000 today. The length of a typical jail sentence rose by 13% between 1996 and 2006 to 25.2 months, but has fallen from a peak of 25.9 months. Government figures also show the number of jail sentences handed out by the courts began to fall between 2005 and 2006, down 3% for crown courts and 7% for magistrates.

Richard Garside, director of the Centre for Crime and Justice Studies at King’s College London, said: “The current overcrowding crisis at most is merely intensifying the long-term problem of prisons entrenching, rather than addressing, crime and offending.

“Ministers have exacerbated the problem by setting targets for the police and other criminal justice agencies that, as our research shows, often have little if anything to do with reducing crime or increasing the safety of the public. This is an argument for reducing our reliance on prison as a means of responding to crime, not building ever more places in response to ill-thought-out policy initiatives.”

Fuller is the first chief constable from an ethnic minority background, and he is seen as a possible future commissioner of the Met. His rivals for the highest job in British policing are Ulster’s top officer, Sir Hugh Orde; Bernard Hogan-Howe from Merseyside; and Sir Norman Bettison from West Yorkshire.

Fuller became Kent’s chief constable in 2004 after a 26-year career in the Met. He helped set up Operation Trident, tackling gun violence within African-Caribbean communities, and is a former chair of the Black Police Association. Fuller is also believed to be the only chief constable who is also a qualified barrister.

In the interview, Fuller also took aim at the government’s attempts to ensure the police are up to scratch. He said up to 13 bodies had the right to inspect his force: “There’s always somebody inspecting us, or we’re under the threat of inspection. It is a constant inspection process. Probably at least a third of my time is spent dealing with inspection, inspection processes, preparing for inspection, accounting to inspection bodies.” He said some inspection bodies made contradictory recommendations: “It actually takes us away from our core role. There’s been too many targets… We’ve been over-inspected by too many agencies who often don’t cost their recommendations, who often don’t talk to each other or share information…”

He said accountability was important, but this was best done at a local level: “There is more benefit in being locally accountable than being accountable to central government bodies.”

Fuller said his force faced this level of inspection despite performing well.

He refused to comment directly on the claim of racial discrimination bought by Met assistant commissioner Tarique Ghaffur against Sir Ian Blair. However, he said of a series of race claims bought by senior ethnic minority officers against the Met: “Potentially it is very damaging for recruitment if the service can’t be seen to progress BME [black and minority ethnic] officers and retain them.”

Of his own career, he said his race had led him to be the subject of more critical scrutiny: “I’m judged more critically by the media, by my staff, by my peers, because of my colour.”He had received a friendly reception from officers when he took over Kent four years ago. But he told of one officer who, despite having a black chief constable committed to diversity as a boss, had only carried out stops and searches on black people. The officer was caught two years ago and disciplined.

A Ministry of Justice spokesperson said: “Public confidence in the criminal justice system has increased significantly in recent years and we are working hard to bring more offenders to justice and to improve services to victims and witnesses. Since 1997 the government has increased prison capacity by over 23,000 places. Sentencing in individual cases is a matter for the courts.”