GORDON Brown has branded Boris Johnson a purveyor of “narrow, dogmatic nationalism,” who, if he became Prime Minister, would risk collapsing the 300-year-old United Kingdom.

The former Prime Minister claimed the Union was more in danger now than at any time in the past 300 years, including during the 2014 Scottish independence referendum.

And in a speech in London this morning, he also attacked the SNP’s desire for independence, referencing the recent D-Day commemorations, which paid tribute to the English, Scots, Welsh and Irish soldiers who fought and died side by side.

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“They fought not as separate nationalities but as one for a common cause. It mocks their sacrifices to wish a bitter partition of the United Kingdom which they gave their lives to save.”

The SNP responded by dismissing Mr Brown's intervention as "tired" and "out of touch," claiming the chaos at Westminster was making the case for Scottish independence.

The former Labour leader warned that the twin threats of Scottish Nationalism and English Nationalism meant that barely five years after the independence poll the country was once again “in a battle for the very existence of Britain".

Speaking at an event organised by the Fabian Society and Hope Not Hate at Westminster Cathedral Hall, Mr Brown launched an excoriating attack on the frontrunner for the Tory leadership.

He accused Mr Johnson of risking landing the UK with an “all-out economic war” with the EU by being prepared to not pay some of the £39 billion divorce bill.

By threatening a no-deal on October 31, the former Labour leader said the Tory frontrunner like the Brexit Party’s Nigel Farage was prepared to sign up to an “act of economic self-harm,” which they had made into a test of true patriotism.

“Talking up no-deal means renouncing the chance of a positive post-Brexit relationship with the continent and our major economic partners: it is yet another example of an inward-looking, isolationist and dogmatic approach that has no economic logic and runs counter to our long-term national interest.

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“And yet those who do not go down that road are accused of not being true patriots and of betraying Britain. Our patriotism has been hijacked by a narrow dogmatic nationalism,” declared Mr Brown.

But the former PM said Mr Johnson was not only defining his patriotism as being anti-European but also anti-Union.

He explained: “Look at what he has written on the Union - not in the heat of the moment during a referendum - but continuously over 20 years. What his writing adds up to is a manifesto vehemently opposing the three constitutional pillars upon which today’s Union is built: Scottish representation in the UK Parliament; Scottish devolution and Scottish funding.”

Mr Brown said the former Foreign Secretary believed:

*the number of Scottish MPs in the UK Parliament should be substantially reduced, arguing that Scotland was grossly over-represented at Westminster;

*the Scottish Parliament making its own decisions in devolved areas such as universities and social care should be curtailed and

*the financial linchpin of the Union, the 40-year-old Barnett Formula, was “reckless” and “unfair to England”.

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Mr Brown went on: "The SNP think of him as their best recruiting sergeant for independence. And not surprisingly few Scots believe the Union is safe in his hands, fearing whether through ignorance carelessness or malice he will be prepared to play fast and loose with the Union when it suits his personal electoral needs.

“Unless he specifically rules it out, he will almost certainly…play the ‘English card,’ whipping up English nationalistic fervour against Scotland for English votes that put at risk the Union itself.

“And if the Scots were in dire need he would have an answer: ‘I propose that we tell them to hop it.’”

The former premier told his audience that it was now “time to draw a line in the sand,” to call on the tolerant, fair-minded, decent, patriotic majority of the British people, who include millions of Leave voters as well as Remain voters, to speak up against the “hijacking of our patriotism”.

He called for a “more informed democracy” by establishing a number of citizens’ assemblies and an updated national strategy for improved community relations.

Mr Brown also launched an attack on the position of Nicola Sturgeon and her SNP colleagues, arguing Brexit meant the case for Scotland’s role in Britain was “strengthened not weakened”.

Recent developments, he said, had demonstrated the scale of the nation’s trading links with the rest of the UK, the sheer complexity of our interdependence, and the heavy costs of a break-up and the real benefits of co-operation.

“The SNP says that with the threat to £14 billion of trade with mainland Europe and 200,000 jobs dependent on it, the Scottish economy faces a crisis.

“But Scotland has £50bn of trade with the rest of the UK and how much more damaging is the risk to the one million jobs and the thousands of companies which depend on trade across the Scottish border?

“The SNP says that we should not disentangle ourselves from 40 years of integration with the EU because of the economic damage that will be done but just how much more difficult would it be for the Scottish economy, jobs and investment if we attempt to disentangle 300 years of integration and interdependence within the United Kingdom?

“It is now urgent that those who support Scotland's role in the UK put the case against the two divisive extremes, Nationalist and Conservative, that threaten to blow the United Kingdom apart.

“Make no mistake, we are now in a battle for the very existence of Britain with two views of our future competing against each other.”

The former PM argued that being a multinational state had made Britain more tolerant and outward looking.

“Being a multinational state has made us more fair-minded and less prejudiced, more respectful of diversity and less antagonistic to minorities.”

Mr Brown insisted these values had to be defended.

“Of this I am sure: if we engage with each other we will find people are far more tolerant, fair-minded and less inward-looking and less dogmatic than those who have hijacked patriotism, turned it into petty nationalism and today dominate our politics with such disastrous results.

“There is one other spur for our actions. A few weeks ago as we commemorated the 75th anniversary of D-Day, we were reminded that English, Scots, Welsh and Irish soldiers are buried side by side in the battlefields of Europe, together in death as they were in life.

“They fought not as separate nationalities but as one for a common cause. It mocks their sacrifices to wish a bitter partition of the United Kingdom which they gave their lives to save,” he added.

In response, Tommy Sheppard for the SNP said: “This is a tired, out of touch intervention from Gordon Brown, whose comments simply highlight the growing divide which is seeing Scotland’s needs utterly ignored and disregarded by Westminster.

“That is what is driving more and more people towards independence as they see – unlike Mr Brown – that Scotland’s interests can only be properly protected by becoming an equal, independent European nation," declared the Edinburgh MP.

“People across Scotland know that they now face a clear choice over their future as a prosperous independent country or shackled to an insular Brexit Britain with politicians like Boris Johnson and Nigel Farage running the show.

“The case for independence is being strengthened by the day through the chaos at Westminster, which has now turned its focus on which of the Tory leadership candidates can deliver the most extreme form of Brexit while Scotland is forced to suffer the consequences,” added Mr Sheppard.   

But Pamela Nash, Chief Executive of Scotland in Union, said Mr Brown's intervention was "timely and important".

The former Labour MP said: “If Nicola Sturgeon had her way, Scotland would lose the pound and access to our home market across the UK, leading to a hard border between Scotland and England. This is the last thing we want or need.

“The danger of nationalism, as opposed to patriotism, is that we create a more divided society when we should be working together to build a better future for everyone in Scotland and the rest of the UK.

“The Nationalists will stop at nothing in their campaign to break up the UK, so those of us who believe in the UK must work harder than ever before to protect communities, workers and families from the SNP’s reckless plan,” added Ms Nash.