David Cameron may well have privately resolved that there is no cause for him to step down if Scotland votes for independence in a few months’ time, as per James Chapman’s scoop today. But the problem is that it is not in the Prime Minister’s gift to make that decision. He may well say that he isn’t going to resign, but that would have no effect on the number of letters that would be sent to 1922 Committee chairman Graham Brady demanding a leadership contest.

It’s not as though the Tory party will reel from the shock of Scotland leaving, then wait to see what the Prime Minister says and then if he says he’s staying, they all get back to their day jobs. The referendum is the single event that his swing MPs all mention when asked what could seriously trip the Prime Minister up in their estimation between now and 2015. Just saying you are not going to resign does not stop the letters flooding in.

Whether those letters are sent or not in the event of a ‘Yes’ vote does depend to some extent on the standing the Prime Minister enjoys with his party, but would be foolish to assume that even daily bacon butty breakfasts at Number 10 would entirely cushion the blow to Cameron’s authority if the Union were rent asunder on his watch.

It’s also worth noting that some of the most serious blows to the PM’s authority didn’t leave him quite as bruised as many expected. The worst blow was Parliament rejecting the Prime Minister’s motion on Syria, which many thought would be curtains for him, or at least leave him wounded and weakened. It did no such thing. So it is difficult to make any confident predictions about where a ‘Yes’ vote would really leave the Prime Minister, save that he will not be the one who decides whether he does stay or go. It will be his party.

Tags: David Cameron, Scotland, Scottish independence, UK politics