But how? I scrabble in my bag for my purse, open it — and there’s my VISA card, staring up at me. I take it out and run my fingers over the glossy surface. Someone must have pinched it from my purse, used it — and then put it back. It must be someone I know. Oh my God. Who?

I look suspiciously round the office. Whoever it is, isn’t very bright. Using my card at Millets! It’s almost laughable. As if I’d ever shop there.

“I’ve never even been into Millets!” I say aloud.

“Yes you have,” says Clare.

“What?” I turn to her. “No I haven’t.”

“You bought Michael’s leaving present from Millets, didn’t you?”

I feel my smile disappear. Oh, bugger. Of course. The blue anorak for Michael. The blue sodding anorak from Millets.

When Michael, our deputy editor, left three weeks ago, I volunteered to buy his present. I took the brown envelope full of coins and notes into the shop and picked out an anorak (take it from me, he’s that kind of guy). And at the last minute, now I remember, I decided to pay on credit and keep all that handy cash for myself.

I can vividly remember fishing out the four £5 notes and carefully putting them in my wallet, sorting out the pound coins and putting them in my coin compartment, and pouring the rest of the change into the bottom of my bag. Oh good, I remember thinking. I won’t have to go to the cash machine. I’d thought that sixty quid would last me for weeks.

So what happened to it? I can’t have just spent sixty quid without realizing it, can I?

“Why are you asking, anyway?” says Clare, and she leans forward. I can see her beady little X-ray eyes gleaming behind her specs. She knows I’m looking at my VISA bill. “No reason,” I say, briskly turning to the second page of my statement.

But I’ve been put off my stride. Instead of doing what I normally do — look at the minimum payment required and ignore the total completely — I find myself staring straight at the bottom figure.

Nine hundred and forty-nine pounds, sixty-three pence. In clear black and white.

For thirty seconds I am completely motionless. Then, without changing expression, I stuff the bill back into the envelope. I honestly feel as though this piece of paper has nothing to do with me. Perhaps, if I carelessly let it drop down on the floor behind my computer, it will disappear. The cleaners will sweep it up and I can claim I never got it. They can’t charge me for a bill I never received, can they?

I’m already composing a letter in my head. “Dear Managing Director of VISA. Your letter has confused me. What bill are you talking about, precisely? I never received any bill from your company. I did not care for your tone and should warn you, I am writing to Anne Robinson of Watchdog.”

Or I could always move abroad.

“Becky?” My head jerks up and I see Clare holding this month’s news list. “Have you finished the piece on Lloyds?”

“Nearly,” I lie. As she’s watching me, I feel forced to summon it up on my computer screen, just to show I’m willing.

“This high-yield, 60-day access account offers tiered rates of interest on investments of over £2,000,” I type onto the screen, copying directly from a press release in front of me. “Long-term savers may also be interested in a new stepped-rate bond which requires a minimum of £5,000.”

I type a full stop, take a sip of coffee, and turn to the second page of the press release.

This is what I do, by the way. I’m a journalist on a financial magazine. I’m paid to tell other people how to organize their money.

Of course, being a financial journalist is not the career I always wanted. No one who writes about personal finance ever meant to do it. People tell you they “fell into” personal finance. They’re lying. What they mean is they couldn’t get a job writing about anything more interesting. They mean they applied for jobs at The Times and The Express and Marie-Claire and Vogue and GQ, and all they got back was “Piss off.”

So they started applying to Metalwork Monthly and Cheesemakers Gazette and What Investment Plan? And they were taken on as the crappiest editorial assistant possible on no money whatsoever and were grateful. And they’ve stayed on writing about metal, or cheese, or savings, ever since — because that’s all they know. I myself started on the catchily titled Personal Investment Periodical. I learned how to copy out a press release and nod at press conferences and ask questions that sounded as though I knew what I was talking about. After a year and a half — believe it or not — I was head-hunted to Successful Saving.

Of course, I still know nothing about finance. People at the bus stop know more about finance than me. Schoolchildren know more than me. I’ve been doing this job for three years now, and I’m still expecting someone to catch me out.