Politics today is mostly just a turgid clash about yesterday. On our neighbouring island, the structural deficits, stuttering activity and splintering cohesion barely feature. Of course, Brexit was a shock. But it is best understood not as a shuddering break with the past, but as just the latest step in a jagged retreat. From the Empire on which the sun never set to the fragile Kingdom of today, the march inwards and backwards has been quickening for over a century. Wrapped in bunting and felling statues, the mass distraction of small boats and royal spats now dominate. Fuelled by polarised…