Cameron's six month dog's breakfast

I only saw a headline for this yesterday but David Cameron has announced that he wants there to be a six month limit for new Prime Ministers who come to office without having been subject to a General Election. After this limit they would be forced to dissolve parliament and go to the country.

This has set a number of thoughts/questions off in my mind:

• I cannot find any mention of this policy in the Conservative Manifesto. They only published it two weeks ago. Why is it not in there?
• We have a parliamentary system, not a presidential system. Although I think it is probably better that a PM gets their own mandate it is not necessary and it would seem odd to compel this to happen in isolation without other reforms.
• For example, what is to happen if a PM dies in office? I don't think it is a good idea under these circumstances for a successor PM to be forced to go to the country. In a properly Presidential system we might see something like a Vice President who runs on the same ticket as the Presidential candidate and in effect inherits the mandate upon the death of the President. Would we have something like that here? A Vice Prime Minister? And if so, what powers would that person have whilst the PM was still alive? We would also need to think about how a successor Vice PM could be chosen under these circumstances too.
• Incoming PMs usually have a honeymoon period. They vary in length but an effect of this would probably be for a PM who accedes outside of an election to go to the country within a few weeks to capitalise on their likely high ratings. They would have little to lose given that they would be forced to do so in a few months' time anyway.
• For a party that bangs on about stability in government all the time this seems like a potential recipe for a less stable situation.
• If we go down this road, we are making our system more and more presidential. There will be unforeseen consequences to this as our unwritten constitution adapts to accommodate it. Now these consequences may not necessarily be bad but surely it would be better to plan out things like this properly rather than just fiddling with little bits of the constitution without any broader idea of the likely effects.

And I think that last point sums it up for me. This smacks of the worst kind of tinkering of the sort Tony Blair was frequently guilty. I remember how he wanted to abolish the position of Lord Chancellor and indeed if I remember correctly it was actually announced. Then someone pointed out that this was not actually constitutionally possible and they quickly had to scurry around in the background making rushed changes to their proposals so that they could work.

I had hoped that the Conservatives would have learned from things like that announcements on the hoof that are ill-thought through often leave more problems in place than they solve but apparently not.