A perfect match

He is the son of Sir James Goldsmith and has got billions in the bank, while she is a hippyish, wild thing with a mere £18 million or so to spend. The wedding of Ben Goldsmith to Kate Rothschild in September will unite two great dynasties. But, asks Jonathan Cooper, is it a marriage or a merger?

THE GROOM

Who is he? Old Etonian Ben Goldsmith, 23, is the son of Sir James and Lady Annabel Goldsmith. He is the younger brother of Zac, editor of The Ecologist, and Jemima, wife of Pakistani cricketerturnedpolitician Imran Khan. He has been named Britain's most eligible bachelor by Tatler magazine.

So he's handsome, tall and impossibly elegant? Ben-Ben, as his family and close friends call him, takes after his mother in looks. He is a bit fey, has what one friend calls a "wicked grin" and "a great sense of humour", and talks 19 to the dozen.

So what has he got from the Goldsmith family? Money. Lots of it. How much we couldn't tell you exactly. His fortune is tied up in trusts, which are so convoluted that his late father boasted they could never be unravelled. When Sir James died he left assets worth about £1.2 billion, and each of his children was estimated to have received £10 million spending money.

Did he inherit anything else? His father was a huge gambler, and Ben likes a flutter. In 1999, he said he bet £500 on Montjeu, a champion horse bred by his family - the equivalent of two weeks' allowance. He won. Like his uncle Teddy and his brother Zac, Ben is a great believer in the environment and everything green.

I presume he doesn't work for a living? No, but he is aware of the power of money. When he was four, he lived next door to a golf course. "I used to run around collecting balls that landed in our garden, then sell them to people who came for Sunday lunch," he says. He is also a shareholder in quintessentially.com, an internet business designed to relieve the wealthy of the stresses of everyday living (ie getting preferential rates and bookings in restaurants, hotels and gyms). It charges £650 a year for its services.

More recently, he has invested in Marco Pierre White's new venture, Drones, a £350-a year private dining club. Last year, Ben-Ben also announced he was setting up an ecological equities fund to invest primarily in renewable energy. "I'm looking to raise £30 million," he said. "This business will be bigger than the internet one day."

Isn't he a bit young to be getting married? Not by Goldsmith standards. Zac was 23 when he married Sheherazade Ventura, daughter of socialite Viviane, while Jemima was 21 when she wed Imran. Jimmy Goldsmith famously eloped to Gretna Green aged 21 with Bolivian tin heiress Isobel Patino.

Anything bad to report? No, he's clean as a whistle, although one friend recalls him bombarding golfers with eggs on the course near his parents' Richmond home, before adding: "He's really not spoilt at all. He's a bit shy, but really just wants to be one of the guys."

Who will they be inviting to the wedding? The young, rich and well-connected, naturally. Among the 600 guests will be James Tollemache of the brewing family, whose wild 21st birthday party ended with Prince William jumping into the family moat; quintessentially.com founder Ben Elliot; Tom Parker Bowles; Alexander Spencer-Churchill; Lord Freddie Windsor, the son of Prince Michael; and Prince William. Anyone not invited will be socially dead.

THE BRIDE

Who is she? Kate Rothschild, of the banking dynasty

Appearance? Very pretty. Short, mousy-haired, with green eyes and an air of flirtatious mischief that belies her English rose appearance

Ah. A character, then? "She was very wild when she was at school," says a society figure. At Bryanston she was known as a girl who really liked to party: "Most of the sixth-formers were in love with her. She would go up to London at weekends and really go out on the town."

Isn't she a bit young to get married? She will be 21 at the time of her wedding. Her late father Amschel was 25 when he married her mother Anita Guinness, 23.

Hang on. We know she has Rothschild blood, but Guinness, too? Yes, Anita is the daughter of James Guinness, from the merchant banking side of the brewing family. Her sister Sabrina once dated Prince Charles (and Mick Jagger). She is extremely wealthy in her own right.

So, a charmed life? No. Her father killed himself at 41 in Paris in 1996. He had joined the family firm only nine years earlier. The halfbrother of Lord (Jacob) Rothschild, he was being groomed to take over the family bank, NM Rothschild, from his second cousin Sir Evelyn de Rothschild. No one is sure why he killed himself. The weight of responsibility, most believe.

How did this affect her? Before she went away to school, Kate is said to have been "very troubled, quiet and introverted", but has become more outgoing. She is also tougher than Ben. A family friend says conclusively: "She's the one who decides when to move on at a party."

Does she work?She was studying fashion design under Patsy Puttnam, wife of Sir David Puttnam, but has now left to spend the summer organising the wedding at St Mary's Church, Bury St Edmunds, near the family home of Rushbrooke Hall.

She's not a practising Jew, then? No, her mother isn't Jewish, silly. The Rev Wendy Sunderland will be assisting at the service.

Who will she be inviting? She will be inviting Ben Elliot's sisters, Katie and Alice. Tom Parker Bowles's sister, Laura, will be there, as will Lady Eloise Anson and sisters Rose and Marina Hanbury.

And her future as Mrs Goldsmith? She is likely to pursue her own fashion career which, at the moment, tends to hippyish clothing. She is conscious of comparisons with Jemima, and doesn't want to be seen as a style icon. Instead, says the friend, "she brings flip-flops into a stiletto world".

Presumably she doesn't need the money? No, her father left more than £18 million to his family.

Still, I understand there are cynics out there who are calling this a merger, not a marriage? Disgraceful! "When she met Ben-Ben, she fell head over heels and I don't think there has ever been anyone else," says an outraged friend. "She did travel during her gap year, though."