Oh bloody hell. I can’t have Jess telling everyone the decorations came from the pound shop.

‘No!’ I say quickly. ‘Of course this isn’t for Luke! I’m just … getting inspiration. Aren’t you buying anything?’ I add, noticing she doesn’t have a basket. ‘Aren’t you going to stock up on Jiffy bags or something?’

I would have thought this place would be right up Jess’s street. She’s the one always giving me lectures about spending too much and why don’t I buy in bulk and live off potato peelings?

‘No, I don’t buy things any more,’ says Jess matter-of-factly.

Did I mishear that?

‘What do you mean, you don’t buy things?’ I say, still loading up my basket. ‘You must buy things. Everyone buys things.’

‘Not me.’ She shakes her head. ‘Since living in Chile, Tom and I have taken the decision to be zero-consumers, or as near as possible. We barter instead.’

‘You barter?’ I turn and stare at her. ‘What, with beads and stuff?’

Jess gives a snort of laughter. ‘No, Becky. Everything. Food, clothing, heating. If I can’t barter for it, I don’t do it.’

‘But … who with?’ I say incredulously. ‘No one barters any more. That’s, like, the Middle Ages.’

‘You’d be surprised. There’s a lot of like-minded people out there. There are networks, websites …’ She shrugs. ‘Last week I bartered six hours of gardening for a British Rail voucher. That got me up to Scully. It cost me nothing.’

I stare at her, gobsmacked. In fact, to be honest I feel a teeny bit affronted. Here we all are, feeling really virtuous because we’re shopping in the pound shop. And Jess has to trump everyone by not shopping at all, ever. That’s so typical of her. Next she’ll probably invent some form of anti-shopping. Like anti-matter, or anti-gravity.

‘So … could I barter?’ I say, as a sudden thought hits me.

‘Of course you could,’ says Jess. ‘In fact, you should. You can get anything and everything. Clothes, food, toys … I’ll send you links to the websites I use most.’

‘Thanks!’

Yes! I resume filling my basket, full of exhilaration. This is the answer. I’ll barter for everything I need for Luke’s party. It’ll be easy. And those posh, zillion-pound party organizers can sod off. Who needs them when you have a pound shop and a bartering website?

Ooh. Star Wars fairy lights, two strings for a pound! And some Yoda shot glasses.

I pause thoughtfully. Maybe the party could have a Star Wars theme. I mean, I’m not sure Luke’s exactly into Star Wars … but I could get him into it, couldn’t I? I could rent out the DVDs and suggest we join the fan club and I expect he’d be a total enthusiast by 7 April.

Except there are also some really fab disco-ball garlands. And some jewelled pewter-effect platters reading ‘King Arthur’s Court’, with matching goblets. Oh God, now I’m torn.

Maybe it could be a Seventies-disco-Star-Wars-King-Arthur fusion themed party?

‘You could barter for those, too,’ Jess says, watching me disapprovingly as I pick up a disco-ball garland. ‘Or even better, make decorations with recycled materials. It’s far more environmentally friendly.’

‘I know,’ I say patiently. ‘I should have dreary old paper-chains made of newspaper.’

‘I’m not talking about paperchains made out of newspaper!’ She looks offended. ‘There are lots of creative decorating ideas on the web. You can re-use silver foil, decorate plastic bottles …’

Silver foil? Plastic bottles? What am I, six years old?

‘Look, Jess!’ Janice’s bright voice interrupts us and I look up to see her rounding the corner, clutching a small packet. ‘I’ve found some vitamins! Folic acid! That’s supposed to be good for you young girls, isn’t it?’

I exchange looks with Jess.

‘Only if they’re planning to become pregnant,’ says Jess icily.

‘Well, I’ll just pop it in my basket, anyway.’ Janice’s casual air is fooling no one. ‘And look at this! It’s a baby-name book! A thousand names for only a pound! Girls and boys.’

‘I don’t believe this,’ mutters Jess, hunching her arms around herself defensively.

‘What do you need a baby-name book for, Janice?’ I ask.

‘Well!’ Janice’s cheeks grow pinker and she looks from me to Jess. ‘You never know …’

‘I do know!’ Jess suddenly erupts. ‘Listen, Janice. I’m not pregnant. And I’m not going to be pregnant. Tom and I have decided that when we have a family, we’ll be adopting a disadvantaged child from South America. And it won’t be a baby, and it’ll have a South American name. So you can keep your bloody folic acid and your baby-names book!’