What if scenarios are always enjoyable, so let's start the day with this one...
Scenario: Five Cabinet Ministers visit Gordon Brown to tell him he no longer enjoys the support of the Cabinet. He realises the game is up and agrees he will step down but makes clear that he will go immediately and not stay in office until a successor is elected - something that would take at least two months.
Question: what happens then?
Would the Queen be duty bound to call upon Harriet Harman, as deputy leader, to take over in the interim?
I only ask, because if that is the case, then this could be the very thing that saves Gordon Brown's skin. Labour MPs would be horrified. Whatever they think of Brown personally, or as a leader, few of them believe Harriet Harman would be the person to guide the country through two months of economic turmoil. At least in that they would be in tune with most of the country.
On a related note, Brown's defensive position seeems to be that he was a hugely successful chancellor and is therefore best qualified to see us through this economic turmoil. Some private polling I have been told about would suggest that is not quite how the Great British Public sees it. Nine months ago a huge majority of people thought he had been a very successful chancellor. The same question was put a few weeks ago and the figure had dropped to fewer than one on five.