My shifts are Monday and Wednesday 5.45pm to midnight, and Friday to 2am.
After a day at school, it's almost another whole day's work. Coffee does help me stay awake, but I thrive on little sleep: six hours seems plenty.
In August 2002 I was sworn in after Home Office checks, and now I've been promoted to sector officer, in charge of 13 "specials" across Bourne, Stamford, and Market Deeping. When I get in, I review incidents on the computer. Then it might be a case of responding to break-in calls, going out with the radar gun to catch speeding motorists, or tackling the local graffiti problem. Foot patrol is my favourite, though; when the public see the uniform - I keep mine at the station and change at the start of each shift - it provides immediate reassurance.
Friday night is always the busiest. There are hundreds of young people pouring out of the pubs in Bourne and Stamford town centres, and, usually, I'll have to arrest some for being drunk and disorderly. It can get a bit hairy, but we do carry a heavy belt with handcuffs, a baton, and CS spray.
You get used to the jibes directed at you by some of the public. Just as when pupils play up, you can't rise to it. I haven't arrested any former pupils yet, but I did stop an Ofsted inspector for speeding a few weeks ago. He saw the funny side. At interview I was asked: "What would you do if you pulled over your headteacher?" Of course, it would make no difference.
Even heads aren't above the law.
People often ask how I fit it all in. It's just a case of using every hour of the day... I stopped watching EastEnders years ago, and I'm still alive.
But I do like The Bill. Working supply means I don't have the usual planning commitments, and I try to do marking at lunch. Yes, I'm not at home that often, but my wife doesn't complain. Well, not really.
I do police work for the same reason I teach: because I want to make a difference in people's lives. But if I had my time again, I think I'd be a police officer. The impact you make is so much more immediate. True, I haven't caught a Mr Big yet. But as I said, you never know what the next shift will hold.
Ian Davison was talking to David Mattin