THIS week’s Declaration for Independence signed by various literary and media luminaries was significant more for what it didn’t say than what it did.

Mostly it was a compilation of familiar pro-diversity, pro-self-government themes, though with a curious demand that “Freedom of speech ... should adhere to principles of environmental and communal sustainability and responsibility”. Not sure Voltaire would have agreed, but never mind.

But I could see nothing in the Declaration with which the present leadership of the SNP would disagree.

“Free, fair and open society ... protecting the environment ... sovereign right of the people to choose their own destiny”. Yet, I know from speaking to some of those behind the initiative that what they really wanted to say was: For God’s Sake Nicola, Get On With It!

There is mounting frustration in the independence movement at the lack of progress. Nothing new in that, but it is now verging on open factionalism – something the SNP has always avoided in the past. Many activists want the First Minster to stop meekly asking for permission from Westminster for a referendum.

They’re ready to go. The stars are in alignment. Why can’t she see that? The phrase most frequently deployed is “show some leadership”. Well, last week she did, but not in the way her critics hoped.

Nicola Sturgeon took a leaf out of Boris Johnson’s negotiation play book and played hard ball. Her message to the radicals is: forget it. There will be no support for UDI, unlawful referendums, civil disobedience or even mass demonstrations. The First Minister has conspicuously declined to attend any of the recent independence marches, the largest in Scottish history, confining herself to a few warm words.

Nor is the SNP leader prepared to see the party conference debate the so-called “Plan B” of figures like the senior councillor, Chris McEleny, and Angus MacNeil MP. They want to turn the next election into a kind of referendum on independence if Westminster says no to indyref2. But this is just not her style. She is not an insurgent. She is not Alex Salmond.

The only route to independence that Sturgeon will pursue is via a “legal and legitimate” referendum. “It is,” she told the BBC last week, “the only way.” This language was significant. Use the words “legal and legitimate” on social media and you’ll likely incur the wrath of the SNP’s digital warriors, who insist that Scottish independence should not be subordinate to “English law”. She has a solid mandate from the voters.

For many nationalists the idea of letting Westminster decide Scotland’s destiny is tantamount to treachery. As the Declaration puts it, the “sovereign” people of Scotland have the inalienable right to determine their own future. What right has the UK Government to impede the will of the people? Bog off, they say, and take your Section 30 order with you.

Nor are the Plan B supporters particularly interested in the observation that Scotland is split down the middle on independence and that a referendum could turn out to be as divisive as Brexit. They’re convinced there is a latent majority for independence, if only someone were prepared to lead it.

Look, they say, at how Alex Salmond grew the Yes support from 30% to 45% in 2014. The next campaign will begin from a much higher base. Support for independence is rising and a clear majority of Scots thinks there should be a referendum in the next five years.

Brexit has thrown the UK constitution into chaos and alienated Scottish remain voters. The most unpopular Prime Minister since Margaret Thatcher, Boris Johnson, seems determined to force Scotland into a disastrous no-deal Brexit. Times like this will never come again.

They may be right. Once Brexit is resolved the whole independence question may change, as the Scottish people settle into the new constitutional arrangement.

It will no longer be a case of saving Scotland from the madness of Brexit, because the UK will already have left the EU. Scots will have to come to terms with a new constitutional reality, which makes independence that much harder precisely because Scotland and England will no longer be in the European Union. The Irish border question will move to Carlisle.

Indeed, the arguments will probably turn on whether and how Scotland can secure the soft Brexit that is apparently being proposed for Northern Ireland. It is staying in regulatory alignment with the European Single Market, which gives a huge advantage to firms located there. Should Scotland not have equal friction-free access to the ESM? Why is Scottish consent not an issue?

These are important questions, but they are not essentially about delivering independence. It will be more like negotiating a new kind of devolution. The idea of breaking away from the UK altogether could become sidelined – as it has for the last two years. There is, anyway, trouble ahead for the party with the Alex Salmond rape trial coming down the tracks, preceded by rumours that Sturgeon won’t be around very long after it.

But if she goes, it’s not clear that there is anyone to replace her. The party is not exactly replete with charismatic leaders. The SNP has settled into a kind of political middle age, where it is more concerned with day-to-day management – schools, hospitals, tax etc – than with fomenting revolutions with unpredictable consequences.

Why risk losing seats when the SNP dominate Scottish politics? Nicola Sturgeon’s authority in the party is as high as ever, but the loss of nearly one-third of SNP MPs in 2017 was a huge shock. Why risk that again?

The Plan B activists are right about one thing. The Section 30 route to independence is likely to be a very long one. The First Minister is saying she will apply for permission to hold a legal referendum next year. But I can’t see any Westminster government agreeing to a referendum on independence while Brexit is being resolved, and that could take many years.

There will be an extended transition period, and then a long settling-in process to whatever deal finally emerges. The talks about the UK’s future trading relations haven’t even begun.

Moreover, the EU may lose its recent sympathy for Scotland once Brexit is resolved. Brussels is instinctively hostile to secession because many member states, like Spain, have autonomist movements to cope with. The EU has generally regarded regional independence movements as dangerous right-wing populism.

So, Westminster is likely to say “now is not the time” until well into the next decade, and there will be little support, as the FM hinted in her BBC interview, from Brussels. Brexit Britain may well decide that there is never a good time for secession.

Of course, independence is a long game, and Scotland is well on the road to achieving self-government at some point. But for my generation of older independence supporters, that’s small consolation for seeing their hopes come to nought

There is a kind of melancholy settling over the independence movement. The spirit of 2014 hasn’t entirely gone away, but it is rapidly fading, leaving the elder statesmen and women to talk of what might have been.