In the 1970s, an age long before World Cups, rugby union to the British public meant Bill McLaren, rude songs and, most of all, Wales. Between 1969 and 1979, the men in red shirts won or shared eight Five Nations Championships, including three Grand Slams and six Triple Crowns. But the mere facts resonate less than the enduring images of the precision of Gareth Edwards, the sublime touch of Barry John, the sidesteps of Gerald Davies and Phil Bennett,...