Virtually everything I learned about leadership traits and core values, I learned in the Marine Corps. To this day, I keep a list of the traits in a little black book, 14 of them, including integrity, justice, bearing, enthusiasm, endurance - all indicators you aspire to when you're a leader.

I think it's only natural to want to look good. I enjoy good clothes, so 18 years ago I moved to having custom-made suits. They last longer. They fit you better. In my opinion, I think men don't spend enough on clothes.

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.

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.

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've been the longest-serving police commissioner in the history of the department, but it's time in my life to move on. I'm ready for new adventures, new challenges.