One factor is the devolved structure of Britain's police forces. By law the home secretary cannot determine the number of officers each force employs and some chief constables have chosen to spend any spare cash on new technology rather than extra manpower. Another cause has been a squeeze on police budgets - until recently some forces have had to sack officers rather than recruit them. This problem was partly solved by the comprehensive spending review, which provided extra funds for recruitment. But the most significant cause of the problem seems to be the fact that people simply aren't as keen to join the police as they once were.
Officers can no longer afford to live in some of the areas they police.
The reputation of the police has taken a knock, too - partly as a result of the report into the Stephen Lawrence affair and revelations about police corruption, but also through the way the police are portrayed on television. Ministers complain that programmes such as The Bill are simplistic and misleading. These are designed to show police officers as heroic public servants rather than dubious stick-wielders. The TV ads feature real-life heroes such as Falklands veteran Simon Weston and footballer John Barnes describing how despite their own success, they still admire the work done by the police. But the army's had ads for years.