It sounds as though I'm making excuses. But I'm not trying to excuse myself. I did the crime - and now I'm doing the time. It wasn't a completely random outburst though. I know my assessment says that there's something wrong with my personality, but that doesn't mean I'm completely unhinged - just a little off balance. Perhaps I did go haywire for a while there. And I do understand that it was wrong. But I also have to admit that it did feel good at the time. It was the first thing that felt really good, in a very long time.

Sitting here, in the cold light of my cell, trying to set down the reasons I did what I did, even I can see that they look trivial. It was just everything - if that's not too vague. The feeling that I had no real choices about anything at all, was eating at me. Any choice I seemed to have turned out to be a delusion. I had to do a job I didn't like, with people who drove me nuts. I was suffocated by rigid company rules, strangled by government red tape. Even in the middle of summer, I had to wear a shirt and tie. The office always stank of the old coffee, coagulating in the bowels of the percolator. The telephones were a scourge and I grew to hate them.

Yes. I know. It all sounds like a whole bunch of nothing, now I come to explain what was driving me out of my mind. It's the same for everyone, right? So why couldn't I just handle it, like any normal person?

Because I'm not made that way. I don't have an infinite capacity to process and comply with officious demands and other pointless kak. The frustration got to be like a maddening itch that my finger nails couldn't reach. Then, finally, I saw a way to scratch it. As a matter of fact, it sort of started with a more literal itch.

This is last summer.

They organise one of those team-bonding weekends for my department. They 'invite' me to join them. We're all expected to accept the invitation - even me: the office geek. At first I try to refuse - still banging my head against that old delusion of choice. Not my bag, I tell them. I don't do 'bonding' and I'm not what you might call a 'team player'. I wish I were, but I'm not. I can't help it. So my line manager insists, making veiled threats - and only thinly veiled at that. She mentions my six-monthly assessment, my bonus, and how in future, when things get tight, some job losses will be inevitable. I want to tell her to stuff the job, but I need it. All I want is a quiet life. Taking the avenue of least resistance is a life-time habit. So I feel compelled to submit and 'get with the programme'.

But I hardly co-operate.

Day one is murder. We have a 3-legged, cross-country 'treasure hunt'. My right leg is tied to the left leg of a pea-brained telesales trainee - who's loving it. We would have won even if I hadn't stolen the list of answers. The clues are infantile. Any idiot could've worked them out - apart from this bunch of idiots, apparently. The hardest part is getting the babbling fool attached to my leg to slow down so we can walk from clue to clue without breaking our necks. At the end we have a two hour wait for the others to shamble back to HQ.

Day two I disgrace myself. We pair up and (this is supposed to be a 'trust building' exercise, you understand) take turns toppling over backwards and trusting our partner to catch us. She goes first and I step out of the way. Unfortunately, she hurts herself even though there's a thick rubber mat between her and the floor boards. Well... what can I say in my own defence?

I say it's an accident. But, as she points out to our team leader, I made not the slightest effort to catch her. I'm embarrassed and shuffle uncomfortably, head down, looking at my feet. I can't tell them that it just feels unnatural to me, and I'm unable to bring myself to grab the woman as she drops. So then I try to make a joke of it and point out that, not getting caught must also provide a valuable lesson: launching yourself backwards, naively trusting an almost total stranger to catch you, should be expected to result in one or two well-earned bruises. As you can probably imagine, that doesn't go down too well either.

It's on the evening of day two that I reach the nadir of irritation. They take us to an area sometimes used by the army for war games. We're divided into two teams and each of us is issued with goggles and one of those guns that shoots paint. Then we have to wade across a shallow stretch of river to an island covered in trees and scrub. The scrub is a hellish mix of brambles and nettles. One team has to guard a tupperware box with a map in it, and the other team has to try and capture it. Because I refuse to blunder about in the pitch black with the other masochists, they give me the job of standing guard over the map while the rest of them melt into the darkness, ready to ambush members of the other team trying to steal our worthless 'treasure'. The air is thick with hungry midges that, over the course of the evening, drain about a gallon of blood from each of us.

The stupid game ends eventually. The enemy breaks through our circle of defence and I take great pleasure in letting them have it - with both barrels, so to speak. I'm cold, tired and irritable and I badly need to kill someone. So I kill everyone! It's a total blast. After a bit of whining about my indiscriminate slaughter, they all join in - and I'm killed a dozen times over.

When we get back to HQ - a sort of primitive camp with dormitories for male and female prisoners - and clean off the paint, we find that not only are we all itching and scratching insanely, but every exposed millimetre of flesh is bright, angry scarlet. Even in this sorry state: scratched and stung to hell by brambles and nettles and itching like the devil from midge bites - everyone's in a fantastic mood. Why?

Because we let rip for half an hour and massacred each other!

I can't say I noticed the team working any more smoothly when we returned to work, but people did seem less prickly for a while. It wasn't the 'bonding' so much as the getting a whole load of toxic frustration out of our systems that lightened the atmosphere. In any case, that's what gave me the idea. I really hated the whole weekend, apart from that final slaughter.

It wasn't much of a 'plan' and it didn't really start to grow until a few months later, when things began to get on top of me again. My mind kept going back to that night and the catharsis I felt, shooting all those people who'd been annoying me in small ways over a long period. I made a list of all the company employees (banks, insurance, telecoms, cable tv), local government officials (inland revenue, council tax, planning department) and various other individuals who were diminishing the quality of my life. It was a job to track some of them down to where they lived and worked, especially the ones who worked in call centres - but I managed to trace almost 20 of them. I got a couple of those guns and an enormous amount of ammo.

You know the rest. I went out and shot everybody who hacked me off - well, not absolutely everyone, but I got a fair few of them. I'm not a bad shot and you can get them almost point blank when they're not expecting it. And I just carried on with my spree until the police caught me coming out of the tax office.

I lost my job of course. I suppose I would have lost it even if I hadn't gone into work and shot my boss. In court she joked that what most offended her was the red paint that clashed so hideously with her auburn hair. She's quite nice really... when she's not bossing.

That's about it. Then it was now. Only a couple of weeks left to serve. I'm glad they decided not to put me in a nut house. They can keep you indefinitely if they want, in those places. Prison hasn't been so bad. It's no holiday camp. Not sure how to put this. I don't want to make it sound as though I haven't been properly punished but... well, I sort of enjoyed it. I've never been popular. No-one's ever made me feel special, or even particularly respected. And we've all heard horror stories about what can happen to people like me in prison - so I wasn't expecting to find friends here, never mind fans. But when they heard what I was in for, the guys just seemed to light up. I'm cool. Subversive. I managed to plant the toe of my boot in the seat of the establishment, as they see it. Now I have a bunch of mates - admirers even. Frankly, in some ways, I'm going to miss it when I leave.