Why no trigger pull yet? Because it takes time to have a plan. Cameron had no plan, now his successor is left holding the baby. This whole thing is quite extraordinary . . .
Imagine your brother has decided to get engaged to a horrible witch. The day after the engagement is announced he pops his cloggs. Then you discover that in his will he has bequested to his oldest male sibling (you) the task of marrying said witch. And you accept the obligation . . . .
Gender issues notwithstanding, May (the oldest male sibling in this parable - and fitting it is that the wheels of this analogy have already started to come off) is now busy preparing the invitations, selecting the hymns, choosing the bridesmaid's dresses and booking the honeymoon suite. Trouble is, there is a fair chance that on the fateful day, she is likely to punch the witch in the face and leg it. Sometimes there is no shoehorn in Christendom with sufficient peng to ease the flaccid old chap into glory.
We'll see.