B ritons’ attitudes to supermarkets are perhaps as complex and confusing as our antiquated class system . Where you choose to do your weekly shop says as much about you as the car you drive, clothes you wear and whether you say “loo” or “toilet”. I didn’t come up with these rules, you understand – but I’ve always been aware they were there.

Growing up, I implicitly knew, without anyone ever having to explain it to me, that my mum’s grocery affiliations – Sainsbury’s for the big shop, Waitrose for “bits” – put us solidly in the “middle-class” bracket. Our loyalty to the orange-branded purveyor was unwavering and beyond question. Even when I got a teenage gig as a checkout girl at the sprawling Tesco off the dual carriageway, with an enticing discount to match, there was never any suggestion that we might switch allegiance.

Everyone knew that people who did their entire shop at Waitrose were a cut above. People who did regular food shops at Marks & Spencer , however, were part of a different social strata altogether. There’s a reason that author Helen Fielding, in the original Bridget Jones books , conveyed Mark Darcy’s rich, posh credentials via his incredulity at how “cheap” a food shop at M&S was.

Buying the occasional packet of chocolate-covered Brazil nuts or tub of cream cheese-stuffed bell peppers from there was one thing, stacking up gastropub-range ready meals, fancy oven pizzas and mini kievs quite another. The very idea! But no.