THE SNP have called for the Queen to "remain steadfastly neutral" in the next independence referendum after it was claimed she was part of an orchestrated campaign to stop Scots from voting for Yes in 2014.

In an explosive new book, Lionel Barber, the former editor of the Financial Times, alleges that the Duke of York told him just one week before the independence referendum that the Queen was preparing to intervene on the issue.

Barber, who used to be a reporter for The Scotsman, said they had lunch at Buckingham Palace, along with Chinese vice premier Ma Kai, on September 11 - four days after a bombshell poll put Yes ahead of No for the first time.

Former prime minister David Cameron told last year how the poll added to a “mounting sense of panic".

"I can tell you that down in London they panicked," Barber told The Sunday Times.

"There is this scene where I am at Buckingham Palace invited by the roguish Duke of York to lunch with the Chinese foreign minister, and Andrew suddenly half lets loose that the Queen is going to intervene on the Sunday.

"They had clearly planned it... it was very artfully done. I'm sure that David Cameron did the same thing which he later did with Barack Obama who he got to intervene on Brexit.

"I bet, and I can't prove it, that he made a desperate SOS call to Buckingham Palace to set that Sunday thing up... Andrew knew about it."

The claim is controversial as the monarch is supposed to remain neutral on political matters.

The Queen does not speak directly to reporters, but journalists are permitted to ask members of the public to reveal their conversations with her.

But news media around the world seized on comments the monarch made six years ago outside Crathie Kirk - the church nearest Balmoral - when she told a member of the public that she hoped Scots would "think very carefully about the future".

The comments were viewed as hugely significant given their timing.

SNP MP Tommy Sheppard said: "This is shocking and extremely concerning.

"If true, it means that political pressure was applied to the Queen to press her into areas where the monarch should not go.

I would hope that the palace would be able to give reassurance that the Queen will remain steadfastly neutral in the next referendum."