In the twilight world of exiled rulers and royalty, former South Vietnamese President Nguyen Van Thieu remains a subject of speculation and mystery. Flown secretly to Taiwan aboard a U.S. military transport last April, only four days before the fall of Saigon, Thieu spent five months in nearly total seclusion. Then last month, only a few weeks after the departure of his wife Mai Anh for London, the 52-year-old Thieu followed her.

Though the dapper, graying former president is rumored to have spirited away millions of dollars in Vietnamese gold reserves to cushion his exile, he has so far rejected the trappings of luxury. Staying with Mai Anh in his niece Kim's drab brick semidetached home in Worcester Park in South West London, Thieu gives every appearance of the entrenched suburbanite. Gone are the limousines and the servants. On a recent outing with Mrs. Thieu, the ex-president carried his wife's shopping bag, then rode virtually unnoticed on the upper deck of a London bus. "You can photograph us if you wish," he told a pursuing cameraman. "We cannot stop you because it is your privilege." (Mrs. Thieu covered her face with her hands and erupted in giggles as the photographer began snapping away.)

The couple shopped in Woolworth's for paper towels and electrical plugs, then moved on to a grocer's for fruit and vegetables. Waiting at a bus shelter, the Thieus—he in sports jacket and trousers; she in a flowing black pantsuit—worried aloud over the value of their British currency. And when a penny slipped out of Thieu's hand, he hastily stooped to retrieve it.

Although Vietnamese sources say Thieu is looking for a home in the London area, he has not yet applied for an extension of his six-month visa. He refuses all interviews, and laughs off reports of his millions. "It is pure propaganda," he maintains with a smile, "made up by a stupid man and spread by the Communists." He is equally reticent about his presence in England, except to note his interest in the London boarding school of his 14-year-old son, Loc. "I'm here to see about my son's education," he says, "which I never had much time to do before."