Like Downton Abbey and Adele, Samantha Cameron will wow the United States Sam, of course, would have been admitted instantly to the First Wives" Club. The thrill of it: photo-ops with Carla Bruni, who'd pout annoyingly for the camera and quiz everyone about French films; tea parties where Mrs Putin boasts that hubby was wrestling with a polar bear before breakfast; and "wine and cheese" with Mr Merkel, a quantum chemist whose idea of small talk consists of explaining how molecular modelling could save the world. A few hours of this, and Sam Cam would be muttering between gritted teeth: "Thanks, babe, but no thanks." The Bond Street stationers would have been very accommodating, conscious of her special circumstances. Think of the millions she's worth in publicity alone. But Samantha Gwendoline Sheffield Cameron doesn't go in for special pleading - and nor does she want to be part of her husband's political machinery. If she plays the role of doting wife, it is not to appeal to the electorate or to detoxify the Conservative Party. It's because she has her own identity: working mother, socially liberal Tory, trendspotter and setter; a high-earner (before going part-time, she earned a reported £400,000 a year), high-profile but never showy, sulky or spoiled. The British public has grown to like this laid-back executive - and admire the political spouse who supports her husband's work without intruding in his world. She would never hold a weepy press conference to claim she'd been hard done-by. Sam Cam has prudently waited for her feet to be firmly on the ground before setting off for distant lands. Now, with perfect timing, she is ready to step on to the world stage. The daughter of a baronet with a family lineage that can be traced back to the Crusades, she has inherited her illustrious ancestors" sense of occasion: the first official outing could only be to the United States, superpower and "special" ally. It helps that she gets on with the Obamas, and that the President, facing a re-election and global turbulence, badly needs Cameron's friendship. Women from New York to Nevada will be clamouring for the Sam Cam look. They'll want the hairstyle - natural but elegantly layered; the clothes - bold-coloured Roksanda Ilincic dresses with matching LK Bennett shoes; and the designer handbag (Smythson, of course). Sam Cam is the first prime minister's wife to embody everything Americans love about this country. Sarah Brown was too middle-class, Cherie Blair too pushy, and Norma Major too obviously ill-at-ease to wow our cousins across the pond. But Sam Cam ("Don'tcha love that cute name?" they'll enthuse in Tennessee) is as posh as Lady Mary in Downton Abbey, slimmer than Adele, and brainier than Cheryl Cole. She works harder than the Middleton sisters ever have, and like Anna Wintour, British-born editor of US Vogue, Sam's got an eye for style and a head for figures - except you won't risk frostbite if you get close. Expect an American love-in, and healthy returns for UK plc. Brand Sam Cam has taken off.