SHORTLY before the 2014 referendum, I had an illuminating conversation with someone who expressed their opposition to independence with the simple dismissive phrase, “I’m Labour”. “Ok,” I replied, “so what do you think should be the top priority for the Labour Prime Minister of an independent Scotland?”

You could hear the brain screech to a halt like truck tyres on loose gravel. After a few moments pause she said, “But Labour don’t support independence, so if Yes wins there’ll only be SNP governments”.

In my experience, this is not an isolated misunderstanding. It stems from a failure to grasp the difference between the government and the state.

The government are those now in office – the current crop of ministers, pursuing government policy, for which they are collectively responsible to parliament, and through parliament to the people. The cornerstone of a government is its manifesto, or, in a coalition, its coalition agreement. That is the document that sets out what the government will do and how it will do it.

The state is a larger and more abstract concept. It refers to the permanent institutions that make up the body politic: the government and parliament, but also the head of state, the courts, and those vital ‘neutral zones’ which protect the administrative, legal, electoral and financial integrity of the political system.

These neutral zones, which have to be carefully shielded from party politics, typically include, at least in most Commonwealth constitutions, a public service commission and the professional non-partisan civil service, a judicial service commission and the independent judiciary, an independent prosecutions service, an electoral commission, a boundaries commission, and an auditor-general.

These are not flashy institutions. Some might be little known by ordinary citizens, since their impact upon day-to-day life is usually indirect. Nevertheless, they play an essential part in upholding the framework of democracy, the rule of law, human rights, and good governance.

They do this by separating the government of the day from the state-as-such. They ensure that the winners of the last election cannot manipulate the electoral rules to favour them in the next. They provide for processes of governance in which there is some separation of power between those in charge of policy-making and those responsible for policing the integrity of the policy-making process. It’s the difference between team captain and umpire.

If those institutions are absent or weak, the boundaries between government and state become blurred. The judiciary is politicised. The civil service becomes a sink of patronage. The rule of law is undermined by corrupt, incestuous relations at the apex of political life. Those outcomes are not confined to, or necessarily the fault of, any particular person; they are signs of institutional failure – the failure of the state to protect itself from the government.

Maintaining the boundary between state and government should be even more important for a national independence movement. Such movements must necessarily operate as a broad front. The aim of such a movement is to create a new, independent state. Within that state, different parties, led by different people, with different policies and priorities, will contest, through normal democratic processes, to be in government.

A successful national movement must therefore be sufficiently inclusive to find space for all, regardless of party, policy or ideological preferences, who support the cause of independent statehood. This applies even – perhaps especially – when they would not support the same government.

The SNP leadership has been reluctant to talk about the one thing it should be talking about when it comes to independence: the constitutional foundations of the new Scottish state. They may have put it off because they do not want to “divide the movement” over what they see as secondary issues.

Unfortunately, this approach backfires, because without a clear focus on the state, it is all too easy to get wrapped up in questions of government.

This brings us back to the Labour voter. They saw the 2014 referendum as a vote for a new government – an SNP government forever, in which the SNP’s manifesto, as interpreted and applied by the SNP’s leadership, would be country’s governing document. They did not see it as a vote for a new state – an independent democratic Scotland, in which various parties, including Labour, would compete in elections to form the government.

This is not the Labour voter’s fault. It was the fault of the SNP in not setting out its vision of a new state as an end in itself. What should have been presented was a constitution. Instead, the voters got a manifesto with fragments of lightly crumbled constitution.

Parking the constitution until after independence has created the very circumstances that many sought to avoid: a divided movement. If you make the constitution central to the independence movement, people become active in making the case for an independent state, on an agreed constitutional platform, regardless of their views on policy matters.

Former SNP MP Stephen Gethins is this week’s star guest on the TNT show at 7pm on Wednesday