Over a million rain-soaked loyal subjects watched the Queen’s barge and a thousand support vessels bobble along the Thames this weekend to celebrate the Diamond Jubilee. And around the country many more millions joined the festivities at street parties, country fairs, community dances and cake sales.

But now the Union Jacks have been put away, we can sit back calmly and consider the big question raised by this extraordinary spectacle: How is it possible, in a modern democratic age, that 80% of British people (I’m Australian, by the way) still support the institution of monarchy – an unelected, hereditary head of state?

The cover story of this week’s New Statesman magazine attempts an answer, arguing that the Queen has presided over ‘perhaps the most successful brand resurrection in public relations history’. Everything began to go wrong in 1992, the famous annus horribilis, when Charles and Diana separated, Princess Anne divorced and Fergie was caught having her toes sucked by an American. But since then the Royal Family has undergone a brilliant PR makeover: the Queen agreed to pay income tax, minor royals have been cut from the civil list, and the family’s public persona is now tightly managed by a small army of communications professionals.

All of this has indeed galvanised support for the monarchy. But it is a mistake to believe that the royal reliance on a well-oiled PR machine is a modern invention. In fact, the real PR revolution took place in the nineteenth century, when the monarchy was under more serious public assault than we can ever imagine today. And we are still living with the legacy.

First, to set the picture. One of the main reasons people give for preserving the monarchy is that it is a ‘great British tradition’ and a time-honoured symbol of national unity. At royal weddings and anniversaries, hundreds of thousands flock to see the gilded carriage glide by, the ermine cloaks and plumed hats, the gunfire salutes and stately processions (half a million were there to watch Wills and Kate tie the knot last year). Television commentators reinforce the idea that these are ancient customs stretching back into the mists of time, with remarks like, ‘all the pageantry and grandeur of a thousand-year-old tradition’, ‘a pageantry that has gone on for hundreds of years’ and ‘all the precision that comes from centuries of precedent’.

This is largely, to put it mildly, nonsense. Most of these royal ceremonies and rituals, including the latest Jubilee, are creations of the late nineteenth and early twentieth centuries. They are what historians call ‘invented traditions’ – conscious efforts on the part of those in power to subtly influence our beliefs by providing a compelling but illusory sense of continuity with the past.

So why exactly did the British monarchy need to invent traditions, and how did it do so?

Few people today realise that for the first three-quarters of the nineteenth century, the monarchy was an object of public derision and something of a national joke. George IV was ridiculed for his extravagance and womanising, and his marriage to Queen Caroline was an unprecedented public scandal. When he died in 1830, The Times bequeathed him a damning editorial: ‘There never was an individual less regretted by his fellow creatures than this deceased king. What eye has wept for him? What heart has heaved one throb of unmercenary sorrow?’ Can you imagine a national newspaper casting such a verdict on a royal figure (even Prince Charles) now?

Moreover, despite what many people might think, Victoria’s early reign distinctly lacked regal grandeur. As historian David Cannadine points out, her coronation in 1838 was an unrehearsed fiasco: the clergy lost their place in the order of service, the coronation ring didn’t fit and they didn’t bother singing the national anthem. From the very beginning she was criticised in the press for her political meddling and was constantly lampooned by cartoonists.

When Victoria effectively retired from public life in the 1860s, the pressures on the monarchy began mounting. With the extension of the franchise and rise of worker organisations, class consciousness was beginning to rival national allegiance. Between 1871 and 1874, eighty-four republican clubs were founded, and Prime Minister Gladstone worried about the ‘stability of the throne’.

It was in this atmosphere of crisis that a concerted effort was made to shore up the monarchy, and the nation it represented. The solution? To resurrect belief in the institution of monarchy by inventing traditions. From the 1870s, writes the historian Eric Hobsbawm, ‘the revival of royal ritualism was seen as a necessary counterweight to the dangers of popular democracy’.

A new era of pomp and circumstance began in 1877 when Victoria was crowned Empress of India – an invented title bestowed by Prime Minister Disraeli – associating her with the glories of the British Empire. For Victoria’s Golden Jubilee celebration in 1887, colonial premiers were invited for the first time, and their troops paraded in a masterpiece of ceremonial choreography, while the clergy were fetchingly dressed up in a new wardrobe of embroidered vestments and coloured stoles. Following the festivities, the Archbishop of Canterbury noted with relief that for ‘days afterwards, everyone feels that the socialist movement has had a check’. The event was considered such a success that it was repeated ten years later with even more splendour, for the Diamond Jubilee.

In 1901 Edward VII ensured that his coronation would be remembered for its romantic majesty by having a new, fabulously ornate carriage drive him back from the Abbey. He also transformed the state opening of Parliament into a full-dress ceremony, parading through the streets of London and personally reading the speech from the throne. Edward was an innovator even when dead, creating the tradition of British monarchs publicly lying-in-state: a quarter of a million people filed past his coffin in 1910.

Other changes followed, for instance in 1917, when the royal family sought to obscure its Germanic heritage by altering its name from the House of Saxe-Coburg and Gotha to the House of Windsor (a wise move given that at the time British troops were in the trenches opposite the Germans), and introduced the practice of having royal weddings in public rather than behind closed doors.

It was through such invented traditions that the Crown reasserted itself as a patriotic symbol and ensured the allegiance of the labouring classes. The achievements of this political programme are evident today in the overwhelming support for the monarchy, and the fact that there is virtually no serious public debate about a republican alternative. So next time you see people waving their Union Jacks at a jubilee ceremony, a fairy-tale royal wedding or some other lavish royal parade through London, just remember that you are witnessing the results of a brilliant PR campaign designed to mould the beliefs of whole nation.

If you enjoyed this article, you might like my recent book The Wonderbox: Curious Histories of How to Live (Profile Books), on which it is based. My other new book is How to Find Fulfilling Work (Pan Macmillan), part of a new series of guides to everyday living from The School of Life (edited by Alain de Botton).