The SDSR, and the National Security Strategy on which it claimed to be built, have both gone off pretty quickly since being first displayed on the Whitehall fishmonger's slab. There have been strenuous efforts to shut down discussion of this fact, which have only had the opposite result. The more this realisation is denied, the worse will be the damage to reputations and, more importantly, to the status and the security of the country. They are also unsafe for the Government politically and for the Prime Minister personally. 

Margaret Thatcher famously observed of her close adviser William Whitelaw that every Prime Minister needed a Willie. She might have added that every Conservative Prime Minister needs an aircraft carrier — and as David Cameron reportedly observed, this means a carrier that carries fully operational warplanes and armaments, when at sea. What does an aircraft carrier, or a naval task force actually do, if you possess them? Sometimes, rarely, they go to war; but most of the time, militarily, they do nothing in anger. Nothing — but with the latent, poised capability to do everything. 

Latent, poised capability creates an aura of power; and the Royal Navy is the prime national expression of Britain's global military influence. But SDSR has slashed it. Lord Guthrie (a soldier) comments, "The Royal Navy's surface fleet is now smaller than at any time since the reign of Charles II. Our small surface fleet of 19 frigates and destroyers will not be enough to meet the many worldwide tasks and to act as escorts for carriers. As an aside, when I was Chief of the Defence Staff and needed a frigate off the coast of Sierra Leone, the same ship had two commitments at the same time. Unbelievably, it was guarding the Falkland Islands and chasing drug dealers in the West Indies." 

As Fox correctly said, we are surrounded by bad things waiting to happen to us. That they do not occur is neither luck nor accident. The authors of the NSS and SDSR do not seem to understand this elementary truth, relearned in blood in successive generations. Conventional deterrence is about making sure that bad things don't happen, and conventional deterrence is an inextricable intertwining of military capability and perceived determination to use it if necessary. Bluntly, the SDSR weakens both. 

To return to the threat to the Prime Minister: luckily for Mrs Thatcher, she had two aircraft carriers when she needed one. In the South Atlantic, they saved her premiership. Mr Cameron is about to run the risk of having none, not anywhere. Knowingly or not, the SDSR authors have declared a de facto Ten-Year Rule at a time when, as Lord Boyce said in his speech to the Lords, to do so is an enormous gamble with the nation's security. "In the short term," the SDSR authors wrote, "there are few circumstances we can envisage where the ability to deploy airpower from the sea will be essential."