The golden age of British ice cream started with a simple enough gambit: that there had to be a way of packaging the iconic ice cream cone. What if, instead of having to queue up outside a seaside ice cream hut, or a transient ice cream van, you could go into a shop – any shop – and find a cornet waiting for you, pre-made? What if it was fixed so that it was perfect every time – so that a smooth, dense volume of ice cream went all the way down into the cone, so that sauce ran through the ruffles and never fully froze and never dripped? What if you could make it so that it was physically impossible for the ice cream to fall off the cone?

An Italian manufacturer called Spica had already got the formula down in 1959. The success was partly down to the cone Spica designed: a bias-cut, crisp wafer construction that had been sprayed on the inside with a mixture of chocolate and coconut oil, forming a damp-proof barrier between the wafer and the ice cream. But the ice cream was important too. Full-dairy ice cream doesn’t hold up well when you try to pipe it or store it like this. The new ice cream was different. It felt colder on the tongue. It melted quickly but smoothly, with the precision of a racer taking a clean, sharp bend. What you ended up with was a cornet of compactly aerated vegetable-fat emulsion threaded with sauce, serving mainly as a pretext for the chocolate plug.

The ice cream did well in the homeland of gelato, but in Britain, the idea didn’t immediately translate. There’s only so long that wet ice cream can last in a crisp sugar cone before things start to break down, and the turnover of ice cream in a corner shop in Bolton wasn’t like that in a store in Rimini. So, when Wall’s – the biggest name in British ice cream – tried to launch it in the UK in the mid-sixties, it crashed out. It took ten more years of chemical tweaking to hit the impossible sweet spot: an ice cream with the physical qualities of Teflon that could withstand getting knocked around in a freezer cabinet but that also melted in the mouth. Eventually they nailed it, and Wall’s parent company Unilever bought the recipe. In the summer of 1976, the Cornetto entered the British corner shop.

Nearly 7 million Cornettos were sold that summer. You couldn’t have chosen a better time to release an ice cream. It was one of the hottest summers on record, with ice cream season extending long into autumn, and that same year, semi-luxury ice cream chains Baskin-Robbins and Dayvilles both entered the UK market and got people used to the idea that you might pay as much as 25p for an ice cream cone. Walls marketed hard, coming up with a proto-viral campaign - the ‘Just One Cornetto’ song. Within a decade, Cornetto had variants in strawberry, mint, and rum and raisin flavours, and was selling 70 million units a year. It was by far the most popular ice cream Britain had ever produced.

In the world of British ice cream, 1976 was the beginning of an influential fifteen-year purple patch that spawned pretty much every one of the ice creams you find in the freezers today. Go to a shop or browse the menu on the side of an ice cream van. You see the Mini Milks? 1976. Funny Feet – the ancestor of skinless, sculptural ice creams in the shape of Minions and Peppa Pig – debuted in 1980. The Twister, the coiled ice cream and sorbet hybrid? The format was invented in 1982 in Ireland as a strawberry, vanilla and chocolate ice cream, with the flavours it has today – the lime, pineapple and strawberry trifecta – allegedly, incomprehensibly, the result of a schoolgirl’s trip to the Gloucester Wall’s factory in 1987 courtesy of Jim’ll Fix It. Viennetta was invented in 1982. Calippo came to the UK in 1982, although the orange Calippo wasn’t launched until 1988. Feast – a horrible ice cream that seems unkillable in a hard-shelled, cockroach kind of way – was 1983. In 1988, we got Mars ice cream bars. In 1990, Carte d’Or. Bookending the period, was another titan launched in 1990 that surpassed even the Cornetto: the Magnum – the most popular ice cream in the world today.

This sudden leap forward in ice cream culture may seem mysterious, but it is often how things work once food gets to an industrial scale. Change happens quickly, and innovation comes in waves – amplified by economic changes, mergers, acquisitions and low-stakes corporate arms races. In the 1930s it happened with chocolate, with the release of Mars bars, Snickers, Milky Bar, Maltesers, Aero, Ritter Sport, Rolos and KitKats – a chocolate-bar formal repertoire we haven’t meaningfully improved upon almost a century later. Something similar has happened in the last few years: an era of unprecedented creativity in crisp flavourings. The golden age of ice cream was just fifteen years, roughly overlaying the late seventies and eighties, but it saw the biggest explosion of industrial British food culture in the last half century.

When ice cream was popularised in the UK in the late 1800s, it would have been hard to imagine that things would go this far. Italian migrants sold penny lick milk ices on the streets, sellers convening on the canals in the early morning to buy blocks of ice, then dispersing across the city. Milk was frozen with sugar and, maybe, egg; serving glasses were wiped out with an old rag and then refilled to order. Over time, the ice creams became more complex; during the thirties, the catering and cafe empire Lyons made ice cream cakes – campy things like Trocadero Wonder Gateau and Glace Pompadour, with ice cream moulded like a ball-gown skirt.

By the start of the World War 2, there were armadas of men on tricycles selling ice creams under the branding of Wall’s – a sausage manufacturer that had realised, astutely enough, that people weren’t really buying pork pies in summertime and so it probably needed a second income stream – which had been acquired by the progenitor of Unilever in 1922. Ice cream, however, was extraneous to the war effort and restrictions were put on how much dairy and sugar the industry could use. By the fifties, ice cream was more basic than ever; most Lyons ice cream – eventually brought under the banner of Lyons Maid – was rigorously functional: bricks, bricklets, cups, poles and rectangular choc ices.

With the end of rationing in 1954, the final wartime restrictions on food were lifted and spending power increased. During the war, the fleets of ice cream tricycles had been sold and scrapped, but they were succeeded by ice cream vans and convenience stores. Wall’s, which had once sold 90% of its ice cream on the road, now sold 90% from the capacious freezer cabinets of brick-and-mortar shops, from whose owners they could demand exclusivity. All of a sudden, and pretty much out of nothing, there was an opportunity to do something new.

The first technologically cutting-edge ice creams were basic by today’s standards. Take the Lyons Maid Mivvi, a fruit split with a strawberry or orange ice shell around vanilla ice cream on a stick that debuted in 1959. It was simple, but undergirded by some of the most complex technologies of the time. Fruit-flavoured syrup was pumped from plastic arteries into rows of moulds, a two-handed manoeuvre in which the moulds advanced in time with the pulse. Mechanical arms swung the moulds through a cryogenically cold brine bath, a motion just smooth enough to be legible to the human eye, during which a crust of fruit ice a few millimetres thick froze to the contours of the metal. After this, the moulds were inverted with the snap of a flamenco dancer’s wrist, tipping the unfrozen centres into a vat. Then, ice cream was piped into the empty shells through exacting metal mouths and wooden lolly sticks were shot from muzzles lining the sides of the conveyor. A machine like this could make tens of thousands of strawberry splits every hour. After it launched, over a third of the Lyons Maid ice cream sold came on a stick.

Technological changes in the sixties and seventies led to ice creams, predominantly geared towards children, that would’ve been unimaginable even a decade earlier. We got Haunted House ice lollies, which had blue ghosts printed into white milk ice. A new blood-red Dracula-inspired lolly had the craftsman’s line of a medieval gargoyle. As you licked a Magic Monster lolly, the face of Frankenstein’s monster appeared through the ice. Fab – an underskirt of strawberry ice, a wraparound of vanilla ice cream and an outer layer of sprinkle- beaded chocolate – was inspired by Lady Penelope’s FAB1 Rolls-Royce from Thunderbirds.

This particular thread of ice cream was beginning to wear out by the mid-seventies. The products being introduced were popular enough, but they were cheap and mainly bought by kids. Slowly, more people got home freezers, which opened space for bigger, take-home tubs of ice cream and supermarket multipacks of their own-brand lollies. Companies like Unilever had to come up with something bigger and better if they wanted to avoid going the way of Lyons Maid, which is to say, sliding into total irrelevance. When Walls struck gold with the Cornetto in 1976, it was the first of many answers to one simple question that would guide the company’s strategy for the next five decades: ‘How do you sell ice cream to grown-ups?’

In the years after 1976, Walls tried to improve and iterate on the Cornetto without much success. The man who finally managed to do it was Kevin Hillman, a product developer who started at Unilever on a scholarship in 1958 and didn’t leave until his retirement in 2001. For most of that time, he worked in ice cream, doing the imaginative acrobatics that you’d expect from Willy Wonka, but with granular attention to detail in the matter of things like emulsification, viscosity and the complex chemistry of milk. He was once head of product development for Unilever’s take-home ice cream – that is, the big tubs and desserts that you don’t eat on the go (in the ice cream world, all products are divided into take-home or impulse, which refers to Cornettos or anything on a stick).

By 1980, Hillman was a product development manager at the new Wall’s production plant in Gloucester. One day, when looking through a Good Housekeeping cookbook that he’d bought his wife, he saw a recipe for millefeuille: three sheets of puff pastry, each one with around 729 layers of buttery carbs and air, mortared with two layers of thick vanilla custard or cream. Hillman began to wonder what an ice cream millefeuille would look like. You could extrude drifts of ice cream, but instead of sandwiching them with pastry – which would soften and warp – you could interpolate them with the thinnest leaves of chocolate, he thought. Until the late seventies, take-home ice cream was a support act to impulse, but Hillman’s team had begun to experiment with ice creams that were good enough to work a crowd. Wall’s had already tried out Arctic roll, wrapping a log of vanilla ice cream in a jam-slicked sleeve of sponge cake, and there were also experiments in strawberry- and chocolate-flavoured log desserts, the foundations of a sundae compacted into a 600ml rectangular ice cream block.

The earliest prototypes of Hillman’s idea were basic – just the size of a Vesta matchbox, with rigid layers that tasted great but visually fell flat. But Wall’s discovered that if you squeezed a length of steel pipe in a vice until it had an aperture of just a few millimetres, you could extrude very broad, thin sheets of ice cream in an unbroken stream; in time, they also realised that if you increased the output speed, the ice cream would begin to pile up in collapsing sine waves. The engineers worked on adapting the machinery so that the process of plastic extrusion could be used to make something like edible art. In between each of the dozen ice cream layers, they sprayed atomically thin, stracciatella-style layers of chocolate, using an Elizabethan ruff as a visual reference. The result was a dessert the same size as the Motorola 8000X, an early, brick-like mobile phone that debuted that same year. When the team at Wall’s drafted the patent, they described ‘Composite confection products [that] comprise a multiplicity of superimposed extruded thin layers of extrudable e.g. aerated frozen confection, optionally separated by interleaved very thin second confection layers such as couverture thin enough to be at least partly discontinuous.’ But on the streets, they called it Viennetta.