‘It was easy, it was cheap, go and do it,’ sang the Desperate Bicycles on their self-funded debut single in 1977, summing up the punk belief that you didn’t have to be the world’s best musician before getting up on stage or making a record. Twenty years earlier, a previous generation learned a similar message from the skiffle explosion, which put guitars in the hands of many future members of the key British rock groups of the Sixties.