The diner is a gleaming nugget of Americana. When US culture became so dominant and enticing around the middle of the last century, a fair portion of its appeal lay in the chrome and Grease of those egalitarian restaurants. The milkshake was the most important and evocative drink of the diner, if not necessarily the most popular. (That was soda, to be discussed anon.) Milkshakes were there to greet the newly invented, cotching teenagers, who wanted kids' drinks in a semi-grown-up environment.
Sweet and cool and sexy, a milkshake represents the best of being young in summer. The original was a thick whiskey-based affair, a kind of savoury eggnog served to invalids. It turned up on the American east coast in the 1880s and was probably made in a cocktail shaker, hence "shake". By 1900 the booze had gone and milkshakes were made with flavoured syrup, and around 20 years later someone thought of adding Horlicks powder to it to make the first "malted milk", one of the gastronomic epiphanies of modern times.
Ice-cream-based milkshakes became easier to make after the electric mixer appeared in 1922, and the process was further automated by the emergence of CFC-dependent freezers in the 1930s. By this time, the milkshake had entered the mainstream. When Senator Albert Fall testified before Congress in the Teapot Dome scandal of 1922, he compared oil drainage to drinking another person's milkshake through a long straw. Hollywood director Paul Thomas Anderson adapted this into Daniel Plainview's unforgettable "I drink your milkshake" line in the best film of the last decade, There Will Be Blood.
By the 1950s, milkshakes were ubiquitous in American restaurants serving American food. Woolworth stores, five-and-dimes, soda fountains in drug stores, burger joints and diners all served them in various forms. They were and remain tremendously high-margin products, cheap to make but enough of a treat to allow retailers to charge relatively high prices for them. In 1954, a milkshake machine salesman named Ray Kroc heard about a smallish burger joint in San Bernadino, California, which sold so many milkshakes it needed eight machines. The restaurant was run by two brothers, Dick and Maurice McDonald. To sell more machines, Kroc persuaded them to open other locations, which he offered to run. Eventually he bought the brothers out, modern franchising was born, and McDonald's grew (until very recently) to become the largest restaurant chain in the world. It was an empire founded on milkshakes.
Shakes have never been as important in Britain as they were in America, but they had a heyday of sorts in the 1930s and 40s in the now-vanished milk bar. The Milk Marketing Board was founded in 1933 to help a struggling industry, and a Welshman named Griffiths opened the first milk bar in Colwyn Bay around the same time. The first London milk bar opened on Fleet Street in 1934 and within a few years the papers were commenting on the new trend. William Boot's famous telegraph from Ishmaelia is "told and retold over the milk-bars of Fleet Street" in Waugh's incomparable Scoop. But the rationing of the second world war and the growth of the coffee house did for the milk bar and, notwithstanding the laced preparations of the Korova in A Clockwork Orange, milkshakes became associated almost entirely with America. They're now most popular in ghastly American-themed places like Tinseltown and the Hard Rock Café.
In the States, milkshakes retain an old-fashioned, pedestrian identity, their flavours often limited to the conservative triumvirate of chocolate, vanilla or strawberry. McDonald's still sell a good number carrying a disproportionate share of urban myths: that they're made with potato or chicken fat or sluiced with the bodily fluids of McJobbers – you have to admire the patience of the luckless operatives of the chain's Q&A website.
In 2006, the LA Times reported that hipsters had taken to farmer's market strawberry and Montana huckleberry milkshakes, and sales of traditional milkshakes rose the same year. But the trashy, indulgent milkshake is not something that lends itself to fancy experimentation. The best are made with fruit: a bit of stewed rhubarb blitzed with vanilla ice cream and a glug of full-fat milk is stunningly refreshing, and I love, too, the combinations of chocolate and banana, or chocolate and coffee. Worst is the E-numbered fakery of "strawberry": I've always hated such labially pink, laboratory sludginess.
The major difficulty with milkshakes is when to enjoy them. I can't pair a burger with a milkshake, which is like eating pudding and main course simultaneously, but nor does a shake feel entirely suitable as a dessert. Perhaps the best is a late-afternoon, post-barbecue thunk of fat and sugar before a long nap, but you may have a different view. When's the best time for a milkshake, and which flavours are likeliest to bring the boys to the yard?
