After nearly two decades in Britain, Bill Bryson took the decision to move back to the States for a while, to let his kids experience life in another country, to give his wife the chance to shop until 10 p. m. seven nights a week, and, most of all, because he had read that 3.7 million Americans believed that they had been abducted by aliens at one time or another, and it was thus clear to him that his people needed him. §But before leaving his much-loved home in North Yorkshire, Bryson insisted on taking one last trip around Britain, a sort of valedictory tour of the green and kindly island that had so long been his home.