David Cameron has hugely raised the stakes by announcing that he wants to hold a binding referendum on Scottish independence. By proposing that the timing should be brought forward and that Scottish voters be offered a straight choice between staying in or leaving the UK, he has transformed the long game being played by the SNP into a penalty shoot-out. Whether his intervention is in the interest of the country remains to be tested.
The SNP’s strategy has been a gradualist one, to build momentum slowly for independence and to hold the referendum at a time of its choosing, probably in 2014. This strategy was in part forced on it by the limited powers of Holyrood, which cannot declare Scottish independence: only Westminster can do