It should have been very different. Boris Johnson enjoys grand-standing and Glasgow was an ideal venue. There would have been plenty of grounds for scepticism. Even if they had not added to the carbon count, many of COP26’s proceedings would merely have produced the purest hot air. But even if his shallowest qualities had been prominent – which they usually are – Boris would have had fun. Then the fun stopped and the PM became mired in toxic political waste. His faults came to the fore.