 Wales next won the Five Nations outright in 1975 , and in 1976 , Wales won their second Grand slam of the decade . Just like the first in 1971 , they only used 16 players over their four matches . They repeated the feat in 1978 and , in the process , became the first team to win three consecutive Triple Crowns . Following their final Five Nations match of 1978 , both Phil Bennett and Gareth Edwards retired from rugby . 
