Boris Johnson’s approach to the culture war is to wait for the other side to overreach – talk of taking down Churchill’s statue, no singing of Rule Britannia at the Proms – then pile in. So, today he has waded into the row about the BBC’s decision to only have instrumental versions of Rule Britannia and Land of Hope and Glory at the last night of the Proms this year, declaring that ‘it’s time we stopped our cringing embarrassment about our history, about our traditions, and about our culture, and we stopped this general fight of self-recrimination and wetness.