John Walker, the American-born musician who was the frontman for the Walker Brothers, one of the most successful bands of Britain\'s Golden Age of rock \'n\' roll, has died at age 67. Walker died Saturday of liver cancer, his personal assistant, Polly Klemmer, said. He had continued to work until just a few weeks ago, making his last concert appearance in Los Angeles in March, Klemmer said Sunday. He had his greatest success as the guitarist and vocalist for the Walker Brothers, which produced such 1960s hits as \"The Sun Ain\'t Gonna Shine Anymore,\" \"Love Her,\" \"Make it Easy On Yourself\" and \"My Ship Is Comin\' In.\" While the Beatles and other British groups were remaking the face of rock `n\' roll during the so-called British invasion of America in the mid-1960s, Walker moved from the United States to England instead.