Political conferences poison people. It’s not the politics that’s the problem — it’s the three or four days marooned inside a secure zone, fuelled by wine and beer and coffee bars, with the hundreds of fringe meetings all powered by anaemic fatty sandwiches, cakes, biscuits and crisps.

Everyone’s resolve to eat well crumbles in the face of constant temptation. At one early evening fringe I went to, the organisers had 12 trays at the back of the room; nine had cookies and three had cake. Most people crammed their plates with one of each, and while we argued about how…