Aug. 8, 1961 - Angier Biddle Duke, the State Department's chief of protocol, has resigned from the Metropolitan Club in a dispute over its policy of excluding African diplomats. He had belonged to the club more than 20 years and was among its most prominent members. The Metropolitan, founded in 1863, is the capital's oldest and most distinguished club. It's 2,000 members include Cabinet officers, Congressmen and high-ranking military and Government officials. It has no Negro members. Two weeks ago, it was revealed that Attorney General Robert F. Kennedy, who belongs to the club, had appealed to the board of governors to end the custom of excluding Negroes.