Downton Abbey star Hugh Bonneville, golf champion Rory McIlroy and tycoon Richard Branson topped the guest list Wednesday at a White House state dinner for British Prime Minister David Cameron. Another British actor, Damian Lewis, star of HBO\'s wartime miniseries \"Band of Brothers\" and television thriller \"Homeland,\" a favorite of President Barack Obama, was also on the guest list released by the White House. Hearthrob and Oscar winner George Clooney provided the Hollywood glamor from the American side at the dinner in an ornate marquee on the White House lawn, the social highlight of Cameron\'s two-day official visit to Washington. McIlroy, the world number one golfer became a star when he won the US Open last June at Congressional golf club, a few miles north of Washington. Bonneville, plays Robert, Earl of Grantham in the British costume drama Downtown Abbey, which has been a huge hit on US public PBS television. Obama and his guests were to dine on a menu inspired by produce harvested by the White House kitchen garden laid out by First Lady Michelle Obama. Guests were to be offered crisped halibut with potato crust, served on a bed of braised baby kale, shaved Brussels sprouts and micro cabbage sprouts. After a salad course made up of lettuces and vegetables from the Obama garden, the main course was Bison Wellington, billed as a fusing of a classic British dish with a meaty US heartland base. Dessert was steamed lemon pudding, prepared with Idaho Huckleberry. Sauce and all of the courses were to be washed down by American wines. British folk-rock band Mumford and Sons, reputedly a favorite of Cameron\'s wife Samantha and R & B singer John Legend, a fixture at Obama events, will perform after dinner entertainment.