I start, naturally, with the people who sit nearest. Some sigh and grumble about the cost, but dig into their pockets and chuck in the odd heavy coin. The big boss finds a tenner. Within minutes, the bag weighs a satisfying amount and I'm feeling confident.
Get to finance. Stop beside a good-looking young man whose eyebrows look as if they've recently curled up for a good doze in the sun.
"Hello," I say. He looks up brightly.
"Hello," he says back, "What can I do for you?"
"I'm collecting for Melanie Martineau's leaving present."
"She's leaving on Friday."
"No!" he leaps to his feet and rushes to the next-door desk, crying: "Paula! Paula! Guess what?" Paula looks up. "Melanie Martineau is leaving on Friday."
"What?" Paula's voice rises to a shriek.
"Yes!" He claps her about the shoulders and she, disconcertingly, shoots out of her chair and punches the air like a footballer who's just bought a new Ferrari.
"Yesss!" she shouts.
Suddenly, finance is in full-on party mode, and when hamster-brows comes back with a fistful of coins and throws them into the Jiffy bag with the words "There, see what you can get her with this", I accept it with pleasure and move on.
To the land where everyone's forgotten their purse. Eight people in a row say, "Sorry, I forgot to go to the cashpoint", or, "Can you come back? I don't know what I've done with my wallet."
Well, there's a tight-arse in every office. Some people just say they'd rather not, which is their prerogative, and another couple say that they're going to be bankrupted if they keep having to chip in for every leaving present, but drop in stuff that clinks.
Until I get to marketing, and meet Bob. Bob looks rather nice, in a bear- like, under-maintained sort of way. I approach him because he looks the most approachable, and watch the smile on his face replaced by something out of The Exorcist, as the words "Melanie Martineau" pass my lips.
"No, I would not," he growls, and hunches over his flow chart. Then he looks up at my retreating back and says: "What made you think I'd want to give anything to Melanie Martineau?"
"Sorry. I'm a temp. I don't know about the relationships in this office."
"Mmm," says Bob, then apologises for being rude. "Tell me," he continues, "Have you had much luck?"
"Not bad, I think." I rattle my Jiffy in his face. Bob wrinkles his eyebrows.
"Well, I'm jiggered. How many people, roughly?"
"I suppose one in two."
Bob huffs. "Well, what a load of hypocrites. Tell me. Have you met Melanie yourself yet?"
"No. She seems to be out of the office all week."
"Well, that figures. Well, look, this isn't meant to be rude, but let me say one thing. I wouldn't give a present to Melanie Martineau if you held a gun to my head and threatened to blow my brains out, and I know that the majority of the people here feel the same way. Just a warning, in case anyone else reacts as strongly as me."
I don't care to ask why, but he tells me anyway. "Melanie Martineau," he says, "Is the witch from hell. Hell, in fact, sent her back."
I flunk out in marketing, apart from the department head, who slings in the smallest note she can find with a groan. They are the last stop on my route, and, despite this disheartening end, I return to my desk with weighty plunder and a light heart. I've always rather enjoyed the leaving-present thing; it's one of the few opportunities you get to spend a silly amount on flowers.
I tip my booty out on to the desk, to find that, including the tenner and the fiver, I have managed, from 100-odd staff, to collect pounds 19.78 - mostly in 1p, 2p and 5p coins.