The Glastonbury festival has undergone a series of metamorphoses in the 31 years since I first attended as a 15-year-old fence hopper (as, indeed, have I, thank heavens). One of the most significant changes, to pillage Gil Scott-Heron’s famous prophecy, is that the evolution has been televised. Back in 1989, if your boots weren’t on the ground — often a quagmire, though not that year — you missed out on all the fun.