"I have now had some discussions with other constitutional law lecturers - this 5 year fixed term and 55% to call an erection stuff is full of potential for controversy."

I agree though I don't think there is anything much controversial about the 5 year fixed term itself. It is simply taking the opportunity away where a sitting PM could call an election prematurely for no other reason other than he thinks he would win if he goes to the country. The 55% rule is different. At the moment a govt can fall at any time even it loses the confidence of the house by just one vote - and of course that would remain so with a 5 year fixed term. However they seem to be suggesting that a vote of confidence could not be lost on just one vote - but that instead at least 55% of the House would need to have lost confidence in the govt. The only reason I can see for this suggestion is that it ensures that even if the Lib Dems walk over to the opposition benches there probably still wouldn't be enough support for ousting the govt hence there wouldn't automatically be an election. The Tories could carry on as a minority govt hoping they could still get much of their proposals through the Commons on an issue by issue, vote by vote basis. Not so far fetched as that is what currently happens in Holyrood where the SNP are a minority govt. So the 55% rule to me looks like a short term self interest policy for the Tories to ensure they remain in office no matter how unpopular their cuts become.