Oh, my head. If I keep my eyes closed, I may just be able to stop my brain sliding out of the sockets. But that means I won't be able to see the screens, and if I can't see the latest bond prices and FX rates I can't do my job. Not that I'll be any use with a king-size hangover like this anyway. And it's all Rory's fault.

It's been the same every day for at least half the team since Rory abandoned the marital pad in favour of a Docklands penthouse and an 18-year-old called Samantha, who works in the back office. From Rory's point of view, the deal has more than a few merits. For a start, Sam has a drop-dead- gorgeous figure that she's perfectly willing to show off at all times, even at work, unlike the rest of us who spend the whole day playing down our curves because we want to be taken seriously. This means she spends her working hours in a cocoon of appreciative whistles, sighs and compliments from the boys, boosting her ego no end, while Laura, Marlene and I either slide past unnoticed, or find ourselves on the receiving end of dyke jokes.

From the looks point of view, Sam gets less out of the trade. Rory's certainly no oil painting. "Not entirely true," Laura pipes up "He could be the model for one of those Cubist portraits. Look at his wonky nose." True enough, I say, and, after all, there are some fabulously ugly oil paintings around. So we set our alcohol-shrunk minds to working out just what Sam sees in Rory, although deep down we know the shallow truth. Laura's the first one to voice the thought. "Well, of course, he must have an enormous ..." but at that point Rory strides up to talk about some deal and we have to pretend we've been talking about the US markets. "Yes, an enormous potential for growth in the housing sector," I ad lib.

As soon as Rory wanders off again, we return to the subject of what Sam sees in him. "It's obvious," says Laura. "He's got an absolutely enormous salary, and he loves spending it. And she's perfectly happy for him to spend it on her. Her clothes have already got miles better; you don't get that kind of gear at Lakeside shopping village, you know. He's been taking her to Harvey Nicks so he can show her off afterwards."

I ponder this fact ruefully. It is, after all, the key to my terrible, throbbing headache, which not even a crispy bacon roll and a pharmacy- worth of painkillers has been able to tame. Rory, you see, has come over all gregarious recently, and insists on dragging us and his new love out for drinks after work every day.

There is a strict routine to these sorties. We begin in the glossy, chrome- bright surroundings of Corney & Barrow, where we can watch people making asses of themselves on the ice-rink outside and drink lots of vodka. Then we move on to some seedy pub with dark panelling and swirly carpets for more vodka and a packet of crisps. By this stage it's possible to slip away, but it's bad for promotion prospects to do it too often. That means sticking around for stage three.

This involves a taxi ride to the back streets of Mayfair and an "exclusive" late-night club. It's quite clear who is excluded: anyone interesting, anyone tastefully dressed, anyone clever. Laura's theory is that membership is decided by the amount of gold jewellery, particularly for the men. Either way, it is, unfortunately, Rory's favourite hangout, so the rest of us are becoming all too familiar with the place and its strange crew. Mind you, they are refreshingly generous with the measures, which explains why I feel so ghastly today. Anyone who says you don't get a hangover with vodka has obviously never drunk an entire bottle on an empty stomach.

So by the close of business I'm looking forward to an early night. I'm just heading for the door when Rory stops me. "You're looking a bit peaky. Are you all right?" I mumble something about a headache, and Rory looks concerned. "I know the perfect cure. Vodka. Never fails. Come on, no excuses, we're going to the pub."