THE notice in the Forthcoming Marriages section of The Times looked much like any other. “The engagement is announced between Benjamin, youngest son of the late Sir James Goldsmith and of Lady Annabel Goldsmith, and Kate, eldest daughter of the late the Hon Amschel Rothschild and of Mrs James Wigan,” it read.

But while the notice’s format was run-of-the-mill, the marriage that it heralds will be anything but ordinary. It represents not just a union between two of Britain’s wealthiest youngsters, but also a merger of three of the country’s most powerful dynasties: the Rothschilds, the Goldsmiths and the Guinnesses.

Ben, 23, is the son of Sir James Goldsmith, the flamboyant financier who built up an estimated £1.2 billion fortune through his pharmaceutical and banking interests before his death in 1997.

The father of Kate, 20, was Amschel Rothschild who, before his suicide in 1996, had been tipped to succeed Sir Evelyn de Rothschild as head of NM Rothschild in the City of London. Kate’s mother is Anita Guinness, heiress to the brewing and banking dynasty.

Explaining the significance of the union, John Graham, a journalist who knows members of both families, said: “It’s as if the Rockefellers, the Mellons and the Vanderbilts were coming together, although admittedly on a slightly smaller scale financially.”

Another journalist, who works for Tatler, the society magazine, said: “In a way, it’s very old-fashioned; you don’t tend to get dynastic marriages nowadays. In the old days, parents from big, wealthy families used to pair their children up with the children of other big, wealthy families. But that does not happen any more. So it’s a bit of a novelty and exciting for names like Goldsmith and Rothschild to come together.”

One snide observer, however, said that he hoped Ben and Kate’s union would prove more successful than the last time a Goldsmith and a Rothschild teamed up. The comment was a reference to the unsuccessful attempt by Sir James and Lord (Jacob) Rothschild, Kate’s uncle, to take over BAT, the tobacco company, along with Kerry Packer in the late 1980s.

The marriage of Kate and Ben will provide a staggering joint bank account by any standards, but especially for such young newlyweds. Ben has an estimated personal fortune of £10 million to £20 million, while the family trust fund set up after his father’s death is believed to be worth about £1.4 billion.

Amschel Rothschild left £18 million to his wife and three children, and Kate stands to inherit even more millions from James Guinness, her merchant banker grandfather. Her share in the Rothschild bank, whose fortune runs into billions, is not known.

In addition to their wealth, the affluent couple also share a similar history: both families have their roots in the Jewish ghettos of 18th-century Frankfurt. The Goldschmidts, as they were then known, made a small fortune through banking interests in Frankfurt, and became a powerful force in cross-frontier banking. After the invasion of Frankfurt by Prussian troops in 1866, Ben’s great-grandparents moved to Paris, before emigrating to London in 1894. Their son Frank, the father of Sir James, who was 16 when his parents came to Britain, become a Conservative MP, and befriended the young Winston Churchill. But it was Sir James whose business acumen took the family on to the very rich list.

The Rothschilds’ links to the Frankfurt ghetto go back to Mayer Amschel Rothschild, a moneylender, who in the early 1800s sent his sons abroad to establish banks in five different European capitals.

One son, Nathan Mayer, came to Britain and, at 21, set up a banking business in Manchester. After moving to London, he helped to finance the allied campaigns in the Napoleonic wars, quickly building up a banking empire whose clients included monarchs and governments.

Ben’s and Kate’s families are unlikely to disapprove of their union at such a young age. The couple have been dating for almost three years and early marriage has become something of a family tradition with the Goldsmiths.

Sir James grabbed newspaper headlines around the world in 1954 when he eloped with his first wife, Isabel Patino, the Bolivian tin heiress, at the age of 21.

Forty years later, Jemima, Ben’s sister, surprised London society by marrying Imran Khan, the Pakistani cricketer and politician, aged just 21. And Ben’s elder brother, Zac, married Sheherazade Ventura, the daughter of Viviane Ventura,the socialite, in 1999 at only 23.

There is no word yet on when the affluent couple plan to tie the knot, but no matter when it takes place it is set to be the wedding of the year. One observer said the guest list would probably read like the pages of Who’s Who, given the couple’s families’ contacts.

Appropriately, the couple held their engagement party last week at Annabel’s, the Mayfair nightclub named after Ben’s mother, Lady Annabel, who is daughter of the eighth Marquess of Londonderry. It is good to see them keeping it in the family.

Great family mergers

Consuelo Vanderbilt, of the American dynasty, married the ninth Duke of Marlborough in 1895.

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