In my post here I commented adversely on the Conservative/Liberal Democrat coalition proposal, in my words, "to require any vote of no confidence to have a 55% majority against the government" in order to come into effect. This comment related to my reading of the provision in the coalition document which states, in relation to its legislation for a fixed term Parliament that "This legislation will also provide for dissolution if 55% or more of the House votes in favour."
The purpose of this proposal is not, it now appears, what I supposed. The convention requiring a government to resign in the event of a vote of no confidence being passed by a bare majority is, apparently, to remain. The 55% figure is the threshold that would require a new election before the conclusion of the proposed 5 year fixed term. What is intended to happen in the event of a vote of no confidence being passed by more than 50% of the those voting but not being followed by a 55% vote in favour of a dissolution, is that the parties which passed the motion of no confidence should get together and agree a new coalition to form a government which is able to command the confidence of the House.
In this respect, it mirrors the equivalent provision applying to the Scottish Parliament which requires a 66% vote to trigger an early election rather than the resignation of Alex Salmond's government, which would only require a 50% vote.
Put this way it does not comprise the act of constitutional violence that I supposed it did. The downside however is that a no confidence vote not leading to a dissolution would, without proportional representation (which gives rise to a more even spread of party representation than first-past-the-post or alternative vote), require a new coalition government with probably only a small majority. or maybe a minority government with no majority at all, to limp on to the conclusion of the original government's 5 year term, even though it would be likely to have difficulty completing its legislative programme. One could envisage a succession of no confidence votes resulting in increasingly ill-tempered attempts to form new groupings capable of forming a government. The thinking presumably is however that, were a government to be paralysed in this way, there would be sufficient cross-party consensus on the need for a new election as to enable the 55% vote for a dissolution to be passed.
Without proportional representation, it might be easier to require that an early dissolution may only occur following the passing of a vote of no confidence against the government in office, and in addition to provide (in order to prevent the government triggering its own downfall so as to provoke a new election at a time of its own choosing) that only the leader of the opposition may put down such a motion of no confidence.