A few years ago, I made a vow never to attend the O2 Arena again, so monstrous did I find the experience of seeing Prince there. I say “seeing”: I’m told he was there, a minuscule purple dot somewhere on the horizon, but had no proof of it. After that, I vowed not to even think about the place. And, yet, I have found myself at the O2 Arena twice in the past 72 hours.