BLT

A British BLT is usually lifted off a chiller shelf in a cardboard wedge with a cellophane window, and the first thing the thumb finds is the give of sliced bread that has spent the morning beside a tomato. The bacon was cooked hours earlier, so it arrives smoky and pliable, folded or laid in strips, with a thin skin of mayonnaise holding the lettuce in place. At home the same sandwich often takes a rasher of back bacon, a round of loin with a tail of streaky, grilled until it crackles. The shop version trades that crackle for a quiet, salty chew, and the bread is soft white or, at Marks & Spencer, malted brown by the maker's own description.

Peel back the plastic and the smell is smoke first, then the sharp vinegar of the mayonnaise, cold enough to feel on the lip. The first bite is a squeak of lettuce against the teeth, a wet cool slice of tomato, and the bacon arriving last, salty and a little chewy. Everything is the same temperature as the fridge it came from, which gives the sandwich its own quiet pleasure: no part is racing to soften or wilt, because the whole thing was assembled to wait. That patience is what lets it live in a bag through a train journey, a morning of meetings, or a bench in a park at one o'clock.

Lunch in Britain is often a grid, and the BLT sits in it beside prawn mayonnaise, egg mayonnaise, and cheese and pickle. It is the one smoked, meaty option in a row of cold fillings, which may explain why people reach for it on a damp Tuesday when nothing else on the shelf promises warmth. It is also the cheapest way to get bacon into a meal deal, the supermarket bundle of sandwich, snack and drink that turned a single shelf into a daily habit for office workers. The triangle cut is part of the identity: two points to bite, a crust edge to hold, and a cross-section that shows all three layers through the window.

The family around it is short and readable from the pack. Add chicken and it becomes chicken and bacon; add avocado and it is a BLAT; add a third slice and a second filling and the shop calls it a club. The bacon is the variable that matters most, since smoked British bacon gives the chilled version its flavour after hours in the cabinet, and the tomato is sliced thin enough that the bread survives until lunch. Behind the counter at a high-street chain the same recipe goes in a baguette or a toasted ciabatta, but the triangle in the chiller remains the form most buyers picture when they say BLT.

Buying one is a small ritual with its own sounds. The plastic wedge clicks out of the fridge door, the barcode beeps at the self-checkout, and the pack is opened on a knee, a desk or a station platform, where the bread has the faint chill of a tray left near the cold wall. The tomato leaves a pale pink stain on the lower slice by the second bite, and the mayonnaise has settled into the crumb enough to taste of the bread. Hands do the work, since the triangle is sized for two mouthfuls and a thumb. Most people finish it in under five minutes.

The BLT in the British chiller

On 14 May 2013 the British Sandwich Association reported its top ten sandwich fillings, and the BLT stood at number one, ahead of prawn mayonnaise in second place, with chicken and bacon and cheese and pickle following. The list covered fillings as sold across Britain's sandwich shops, supermarkets and cafes, and it gave the BLT a ranking that most single-ingredient sandwiches never reach.

No record names the maker or the shop that first put a BLT into a British chiller cabinet. What is documented is where it sits today: Marks & Spencer lists a Bacon, Lettuce and Tomato Sandwich with oak smoked bacon on malted brown bread, and Tesco sells a BLT in its chilled sandwich range. The sandwich entered the British lunch as a packaged, ready-to-eat product, and the 2013 ranking is a measure of how thoroughly it settled there.

The same 2013 list placed bacon on its own in seventh position.