After Theresa May’s £20bn “birthday present” for the NHS, defence secretary Gavin Williamson was mocked for claiming he could “break her” if she didn’t find £20bn for the armed services too. Behind the macho posturing, there is concern in military circles about the depth of retrenchment. It is not new: personnel numbers have been falling ever since the Korean War as spending has been squeezed. The share of national income devoted to defence has dropped by four-fifths since 1953; meanwhile, its share in total public spending fell from 23 to 5 per cent. If our forces still buy the latest kit, they can do so only by buying less— with, for example, sharp cut-backs in the number of tanks and various types of aircraft and naval vessels.