Heavy metal is now over 40 years old. It emerged at the tail end of the 1960s in the work of bands including Iron Butterfly, Vanilla Fudge, Jimi Hendrix, Deep Purple, Led Zeppelin and - most importantly - Black Sabbath. In the 1970s and early 1980s, heavy metal crystallised as a genre as bands such as Judas Priest and Iron Maiden removed most ......
