“The last government defeat over estimates was in 1921 … nowadays any amendment would be tantamount to a vote of no confidence.” (Whener, 2010: p8).

Could we see, in March 2015, the first example of a real conflict within Parliament on the Government’s Budget proposals, leading to a Washington-style impasse? There are several reasons to think that we could, writes Professor Colin Talbot. He argues that the advent of Coalition Government, the Fixed Term Parliament Act, and a general resurgence of Parliamentary power could combine to overturn centuries of constitutional and Parliamentary convention.

There is a dominant myth in Westminster that governments propose budgets and that Parliament has only a “nuclear option” – to accept what is proposed or to reject it, and in effect, pass a vote of no confidence in the government of the day – precipitating a General Election. The above quote is an example of this myth, but by no means the only one that could be cited. It is nonsense.

The basis of this myth – to the extent there is one – is Standing Order 48 of the House of Commons. This states that:

“48. This House will receive no petition for any sum relating to public service or proceed upon any motion for a grant or charge upon public revenue, whether payable out of the Consolidated Fund or the National Loans fund or out of money to be provided by Parliament, or for releasing or compounding any sum of money owing to the Crown, unless recommended by the Crown.”

In plain English, this means simply that only the “Crown” – i.e. government – can propose public spending to Parliament. Parliament can either accept, or reject, proposals to spend money  – but it cannot, as say the US Congress can – make it’s own proposals. This means that motions on “Supply” – i.e. authorising the Government of the day to spend public money – can only be amended to reduce spending in a particular area – but not to increase spending or transfer spending from one area to another.

By convention, this principle has been extended to Finance Bills – which are the Bills that authorise the collection of taxes. Parliament can only propose and vote on amendments which reduce or remove a tax measure, not increase or create a new one. But this is not actually stated in Standing Orders.

Moreover, as the quote at the top suggests, many believe that any rejection or reduction of a tax or spending proposal would be tantamount to a vote of “no confidence” in the government of the day.

This helps to explain why, in over 100 years, there have been only about 20 successful attempts in the British Parliament to amend the Governments proposals for ‘tax and spend’. But interestingly, none of them was regarded as a “confidence vote” and no Government fell and no elections were called as a result of these defeats. The interesting question is – why has this myth become so prevalent that it actually shapes political action (i.e. the lack of rebellions on tax and spend)? And under what circumstances might it change? We may be about to find out.

The 20 or so times there have been revolts in Parliament over specific tax or spend measures in the past century have nearly all been ‘non-Party’ affairs. The political parties – especially the main two – have not sought, in Opposition, to discomfort the Party in office. The main reason for this, as with many other aspects of our quasi-monarchical state, is that they hope themselves one day to be in office and operate the ‘Crown prerogative’ powers of the executive.

Two factors may be about to change that. The first is the Fixed Term Parliament Act of 2011. This lays to rest, at least in law, the idea that any defeat on a finance or supply motion is automatically a vote of (no) confidence. It spells out precisely what does constitute a vote of confidence – including a precise form of words – so there is no longer any ambiguity or uncertainty. Defeat on a finance or supply motion is not a vote of no confidence. It might cause huge problems, but it would not automatically lead to an election.

The second is the advent of Coalition government. We have already seen that as a direct result of a two-Party coalition Government, debates about tax and spending options have moved further out of the realms of the “private government of public money.” It is simply much harder to sustain the “private government” of tax and spend in these circumstances. And as the May 2015 General Election approaches, tensions between the Tories and LDs could make this even more the case.

All this is also in the context of the most rebellious Parliament’s in modern history. There have been more rebellions in the three years of this Parliament than in the period 1945-61 combined – covering 21 years, six parliaments and six Prime Ministers. (Source: Philip Cowley and Mark Stuart’s research).

So here is a possible scenario based on the two changes mentioned above. In March 2015 Chancellor George Osborne proposes a highly political Budget that seeks not just to differentiate the Tories and Labour, but also the Tories and LDs. It contains some tax and spending proposals – e.g. on welfare – that the LDs cannot endorse and certainly do not want to enter the General Election having been seen to support.

They know that defeating the Government on some symbolically important measure in the Finance Bill or Supply motions will not automatically bring down the Government. What have they got to lose by moving amendments and trying to get Labour and other parties support?

Alternatively the initiative could come from Labour – spotting elements of the Budget with which the LDs are clearly unhappy the Opposition could move its own amendments and seek to split the Coalition parties, in the hopes of inflicting damage on both of them.

It is even conceivable that some ‘helpful’ back-bench Tories might move amendments designed to discomfort their hated Coalition partners.

I’m not sure many MPs have yet registered the implications of the new situation – but some certainly have.  None of the above might happen, but all of it could. As the Chinese curse has it, “may you live in interesting times”. We may be about to get our very own version of the Washington Shut Down – although here it wouldn’t lead to a government shut-down.

•  Joachim Wehner (2010) Legislatures and the Budgetary Process: The Myth of Fiscal Control.