If you are in the business of anointing monsters, you can see why your eyes would light up at a punk act called Bob Vylan. Until last weekend, sure, it might have been a tough sell to proclaim them as an avatar for Britain’s revolting youth: prominent though they might be on the UK’s punk scene, they had about about 220,000 monthly listeners on Spotify – a mere 1,000,000 away from a place in the top 10,000. But then, at Glastonbury, they made the most powerful possible case for broad media attention: they said something controversial about Israel’s assault on...