Wrap

In November 2004 Tesco said that its chicken Caesar salad wrap had overtaken the egg and cress sandwich, long the most popular lunchtime snack in its cabinets. The result is a small piece of national history. Egg mayonnaise and cress, soft white bread, cut in triangles: that was the shape of a British packed lunch, and a flour tortilla rolled round chicken, Parmesan-style dressing and cos lettuce took its place at the top of the cabinet. The wrap had been on British shelves for roughly a decade by then, and Tesco, the country's largest seller of sandwiches, reported selling about 2.2 million sandwiches a week across all its lines.

A supermarket wrap is built for the cabinet it sits in. The tortilla is warmed just enough to roll without cracking along the fold, the filling is laid along one edge, and the whole cylinder is rolled tight and sliced on the diagonal so the cut faces show through the pack, a row of pale spirals with green and chicken at the centre. The sleeve is chilled and fogs a little at the corners. Pull one out and the tortilla is cold, slightly tacky where it met the dressing, with a faint flour smell and a garlicky, anchovy-edged sharpness from the Caesar sauce that rises when the film peels back. Soft tortilla gives under the teeth, and the lettuce is the only thing that crunches.

The format suits the way British lunch gets eaten. A wrap fits a palm and a coat pocket, has no crust to flake onto a keyboard, and stays closed on a train seat because the bread wraps the filling on every side. Because the tortilla is neutral, the filling can carry any flavour a buyer's team can think of, so the chiller reads like a menu of whatever was fashionable that year: chicken Caesar, falafel and hummus, Mexican-style chicken with peppers, bacon and avocado. Tortillas also hold wetter, saucier fillings than sliced bread, which goes to paste at the first dribble of dressing. That tolerance is why a Caesar salad, which would never survive between two slices, became the top-selling lunch filling in the biggest chain in the country.

On the high street the wrap runs hot as well as cold. Sandwich chains and station kiosks warm the tortilla on a flat griddle or in a press, which sears a few brown stripes across the surface, softens the cheese and brings out a toasty, slightly nutty smell of toasted flour. In 2013 the hot wrap was the big new development in the category, with several launches that year. Eaten warm, the tortilla goes supple and a little chewy, the filling steams when the first bite breaks the seam, and the foil or paper sleeve holds the heat in the palm. The cold chiller wrap and the hot griddled one share a name and sell from different counters.

Wrap sales figures differ depending on who counts them. The British Sandwich Association cited wraps at about 2 per cent of the sandwich market in 2005, and Tesco's own statistics a year earlier gave a far higher share of its own lunchtime sales. Later trade figures put wraps near 5 per cent of the market in 2011 and again in 2014. The gap reflects different baskets and methods. What every count shares is a rise from nothing in the early 1990s to a permanent slot beside the sliced-bread triangle, in a market that sold about 2.4 billion sandwiches a year by the Association's 2004 estimate.

How the wrap reached Britain

The wrap came to Britain through a specific supplier. James Beaton, founder and chairman of Discovery Foods, saw wraps in San Francisco and introduced them to the British market in the mid-1990s. The tortilla-wrapped lunch had been taking shape in the United States for some years, where the chain World Wrapps opened in San Francisco in 1995, and the format reached the other side of the Atlantic inside the same decade.

Marks & Spencer, the company that had put the prepacked sandwich on British shelves around 1980, is said to have been slow to see the point, and to have missed the concept at first. Within six months of launch, Discovery Foods was reportedly selling half a million wraps a week, a figure that rests on a single trade interview and carries that hedge. No record names the first British shop to sell a wrap over a counter.

The tortilla outlasted its first sceptical buyer by a wide margin. By the winter of 2004, nearly ten years after Beaton's first deliveries, a chicken Caesar wrap sitting in a Tesco cabinet outsold the egg and cress sandwich that had held the top slot for generations.