Trusty acoustic guitar in hand, Frank Turner surveyed the euphoric, swaying scene before him. “This is a collective effort,” he hollered, reducing the cavernous surroundings of Wembley Arena to the intimacy of a front room. “I’m not doing this on my own.”

As the proverb goes, success has many fathers and the singer’s rise to that epochal 2012 headline slot was very much a team effort. Only nine years earlier his label boss, Charlie Caplowe, was running press for Turner’s ...