This billionaire ecosystem generates a lot of jobs up and down the employment food chain: chefs, gardeners, drivers, nannies, bodyguards, and the agencies that employ them -- not to mention the restaurants, clubs and boutiques where they can while away the day.
The higher echelons of English society must be a veritable minefield for foreigners and/or the nouveau riche.
However, help is at hand from the Harrods personal shopping service, "By Appointment."
Michael Mann, Harrods public-relations manager, was quick to point out that the store "offers a lifestyle service that goes way beyond a concierge service. I'm not talking sofas and beds. If people come into new money, we can advise them where to live, where to find a butler, a chauffeur. Where to buy theater, cinema, polo or football tickets."
Sukeena Rao, who heads the Harrods Personal Shopping group, marvels that: "Eighty percent of last year's Forbes Top 10 list shops with their personal shoppers."
Among the requests from the ultrawealthy clientele: "The craziest thing they've ever been asked to do was kit out [furnish] the interior of a Gulfstream jet in 24 hours," Rao said.
"Everything was thought of, from cashmere blankets on every seat, mini Louis Vuitton bags with Creme de la Mer toiletries for everyone. And all the beautiful air hostesses were decked out in Fendi to board the jet to St. Petersburg."
"By Appointment" knows its customers intimately: They require bespoke (handmade) and exclusive pieces from luxury brands like Balenciaga and Oscar de la Renta, which Harrods will source for them.
And if the billionaire is looking for a gift for a billionaire "already has it all" friend, there is the chance to book a private dinner with celebrity chef Gordon Ramsay -- but, frankly, if you have to ask how much it is, you can't afford it.
Culture vulture billionaires in London have everything at their disposal: world-class galleries, concerts, operas and theater.
They are absolutely drowning in choices where gastronomy is concerned.
There are dozens of top-flight restaurants, serving up a cornucopia of delicacies in addition to the mainstay English dishes of celery and stilton soup, Dover sole, roast beef and horseradish sauce.
And how about a little summer pudding to send you into a hyperglycemic attack?
For those who want to party after dinner, the piece de resistance of nightclubs is the aristocrat discotheque Annabel's where you can hobnob with the whole of Debrett's Peerage -- every viscount or lady and German and Arab prince or Russian czar makes the scene sooner or later.
The spokesman for Annabel's, who wanted to remain anonymous, was very guarded in giving any secrets away about his exclusive clientele.
He did admit that the club had its fair share of royals through the door and that there were always parades of limos clogging up the entrance at closing time.
The club, he says, "was founded 40 years ago by Mike Birley, who wanted to provide a good quality service with attention to detail in an atmosphere where the customers are comfortable. It's like a home from home."
The clientele "comes from all over, but in the last 10 years a lot of wealth has come from the Middle East, Far East and Russia."