Even so, I might write a short letter of thanks. And kind of mention that Luke’s unfortunately taken a turn for the worse.

So before we head off to the supermarket I scribble a polite card to Nathan Temple and drop it in the pillar-box outside. As I stride away I actually feel rather satisfied. I have this whole situation under control, and Luke doesn’t know a thing. I am superwife!

My spirits rise even further as we walk into the supermarket. God, supermarkets are great places. They’re all bright and airy and music is playing, and they’re always giving away free samples of cheese or something. Plus you can buy loads of CDs and makeup, and it all goes on the credit card bill as Tesco.

The first thing that catches my eye as I walk in is a display of specialty teas, with a free flower-shaped tea infuser if you buy three.

“Bargain!” I say, grabbing three boxes at random.

“It’s not really a bargain,” Jess intones disapprovingly beside me. Why did she have to come along?

Never mind. I’ll just stay polite and courteous.

“It is a bargain,” I explain. “They’re giving away a free gift.”

“Do you ever drink jasmine tea?” she retorts, looking at the box in my hand.

“Er…”

Jasmine tea. That’s the one that tastes like old compost heaps, isn’t it?

But so what? The tea infuser is really cute, and I don’t have one.

“You can always find a use for jasmine tea,” I say airily, and toss it into my trolley. “Right! What next?”

I head toward the vegetable section, pausing to pick up a copy of InStyle as I go.

Ooh. And the new Elle is out too. With a free T-shirt!

“What are you doing?” comes Jess’s sepulchral voice in my ear. Is she going to quiz me all the way round the bloody shop?

“I’m shopping!” I reply, and sling a new paperback book into the trolley.

“You could get that out of the library for nothing!” says Jess, looking horrified.

The library? I look at her in equal horror. I don’t want some thumbed copy in a horrible plastic jacket, which I have to remember to take back.

“It’s a modern classic, actually,” I say. “Everyone should have their own copy.”

“Why?” she persists. “Why can’t you get it out of the library?”

My temperature is beginning to rise.

Because I just want my own nice shiny copy! And piss off and leave me alone!

“Because… I might want to make notes in the margin,” I say loftily. “I have quite an interest in literary criticism, you know.”

I push my trolley on, but she comes hurrying after me.

“Becky, look. I want to help you. You have to gain control of your spending. You have to learn to be more frugal. Luke and I were talking about it—”

“Oh, really?” I say, stung. “How nice for you!”

“I can give you some tips… show you how to be thrifty—”

“I don’t need your help!” I retort in indignation. “I’m thrifty! I’m as thrifty as they come.” Jess looks incredulous.

“You think it’s thrifty to buy expensive magazines you could read for nothing in a public library?”

For a moment I can’t quite think of a reply. Then my glance falls on Elle. Yes!

“If I didn’t buy them, I wouldn’t get the free gifts, would I?” I retort in triumph, and wheel my trolley round the corner.

So there, Miss Smarty-pants.

I head to the fruit section and start loading bags into my trolley.

How thrifty is this? Nice healthy apples. I look up — and Jess is wincing.

“What?” I say. “What is it now?”

“You should buy those loose.” She gestures to the other side of the aisle, where a woman is laboriously picking her way through a mound of apples and filling a bag. “The unit cost is far lower! You’d save… twenty pence.”

Twenty whole pence!

“Time is money,” I reply coolly. “Frankly, Jess, it’s not worth my while to be sorting through apples.”

“Why not?” she says. “After all, you’re unemployed.”

I gasp, affronted. Unemployed? I am not unemployed! I’m a skilled personal shopper! I have a job lined up! In fact… I’m not even going to dignify that with a response. I turn on my heel and stalk over to the salad counter. I fill two huge cartons with luxury marinated olives and take them back to the trolley — and stop in astonishment.

Who put that huge sack of potatoes in my trolley?

Did I say I wanted a big sack of potatoes? Did I say I wanted any potatoes?