It was the political equivalent of Halley’s comet. On Tuesday, Boris Johnson underestimated his own achievement. He claimed that the review of defence, security and foreign policy was the most wide-ranging study of those topics since the end of the Cold War. That was being too modest. It is the most important contribution since the Duncan Sandys Defence White Paper in 1957, which set out Britain’s strategy for the Cold War: rethinking and re-organising our capabilities and commitments in order to contain and counter the Russian threat.