You can be stopped if a police officer reasonably suspects a crime is about to be committed, is being committed or has been committed. Every law enforcement agency does it. It's essential to policing.

I think one of the biggest scams in law enforcement is the monitor.

When I had the job of police commissioner, 20 years ago, I was more sensitive, more cognizant of complaints and concerned about public opinion. I've learned to do what I think is the right thing. That lessens the impact of criticism. You get used to a pressurized environment and expect it every day.

If you go into any department store these days, your picture is probably taken 30 times. In London there are 500,000 cameras in public spaces. You have no expectation of privacy in public spaces.

I think I've had a long, distinguished career in public service. It just goes to show you what some politicians will do. They'll say or do anything to get elected. I know all these people. They all claimed to be friends of mine up until their mayoral campaigns. They'd call me on the phone and ask for information or come over here and sit in this chair to get briefed.

No other agency is scrutinized like the police. Everything we do is in a goldfish bowl. We are not the most popular people in society. We do things like use deadly force; we're the bearers of bad news. We're not firefighters, who are viewed as heroic, helping people, with people loving them back. The police have a much more complex and demanding job.

I liked the military life. They teach you self-sufficiency early on. I always say that I learned most of what I know about leadership in the Marine Corps. Certain basic principles stay with you - sometimes consciously, mostly unconsciously.