As China announces retaliatory tariffs of 34% on all US goods, everyone writing about this titanic episode of tit-for-economic-tat will be struggling to swerve the clichés.

Many will be resisting “there are weeks when decades happen” (how about 48 hours?) but “never waste a good crisis” is the one I’ll ask my editors to let through. It must be the lodestar for the politicians and officials gathered in Whitehall’s unglamorous underground rooms trying to pick their way through Donald Trump’s, and now China’s, tariff blitz.