When Ewan McGregor was but a wee lad in a sleepy town in Scotland in the ’70s, some 3,200 miles away in a Manhattan townhouse on East 63rd Street, Roy Halston Frowick was living on a diet of baked potatoes with beluga caviar, chilled Stolichnaya, rent boys and mounds of cocaine piled in Elsa Peretti silver ashtrays.