The Sun 'could reveal more' on Queen Brexit story, editor Tony Gallagher tells ITV News

The editor of The Sun has told ITV News the newspaper is not afraid to reveal more details about the Queen's views on the EU amid a furore over its "Queen Backs Brexit" front page splash.

Tony Gallagher told Political Editor Robert Peston he stood by the story as he launched a strong attack on former deputy prime minister Nick Clegg, who has dismissed Wednesday's report as "nonsense".

"We do know more than we printed," he said. "Part of the reason why we didn't put all of that in the public domain was to protect our sources. We do reserve the right to use some of that information."

He added: "We will defend ourselves very very stoutly."

Scroll down for Robert Peston's full interview with Tony Gallagher

Mr Gallagher said Mr Clegg has "questions to answer" and accused "people close to" the former Liberal Democrat leader for a "smear campaign" aimed at Justice Secretary Michael Gove, who has been touted as a source for the story.

Mr Gallagher staunchly defended his paper's reporting and its provocative headline, which are being examined by the press watchdog, saying the story had a "fair amount of substance" and was based on two anonymous sources.

The recall of the event was very detailed by one of our sources. It's not the first or last time that the Queen has uttered critical remarks about the European Union. We had a second event at Buckingham Palace where the Queen uttered very critical remarks.

Tony Gallagher

The story was based in part on comments the Queen was said to have made to Mr Clegg at a lunch at Windsor Castle five years ago.

The Sun's report is being examined by the Independent Press Standards Organisation (Ipso) after Buckingham Palace lodged a formal complaint.

Mr Gallagher said he would abide by Ipso's rulings and denied his position was in jeopardy if it found against the newspaper.

"I don't think my job is on the line whatsoever," he said.

Tony Gallagher said Nick Clegg had 'questions to answer' over his recollections of a Windsor Castle lunch with the Queen in 2011. Credit: PA Wire

The Palace confirmed Her Majesty remains "politically neutral" over the referendum outcome and added: "We would never comment on spurious, anonymously sourced claims."

Mr Gallagher said the Queen should be encouraged to give her views.

"I think it's marvelous that we're hearing what the Queen's views are," he said. "The idea we should be shielded from what she really thinks is a nonsense."

Prime Minister David Cameron earlier rejected calls for an official investigation into the leak.

Mr Gove, Cameron's Cabinet colleague and close ally who opposes the PM in the EU debate, has been widely touted as the source of the leak but has refused to comment publicly on the claims.

The Justice Secretary was one of four ministers, including Mr Clegg, who attended a meeting of the Privy Council at Windsor Castle in April 2011 on the day it is thought the conversation with the Queen took place over lunch.

Watch Robert Peston's full interview with Tony Gallagher

Mr Clegg dismissed the report as "nonsense" and said it was "appalling ... people want to drag the Queen" into the EU referendum debate.

Mr Gallagher said both Buckingham Palace and Mr Clegg had declined to offer denials of the story before it went to print with their more "robust" responses coming a day later.

He accused the pro-EU Mr Clegg of plotting against Mr Gove.

Among those who are circulating the idea that Michael Gove is (the paper's source are) people close to Nick Clegg who have told lobby correspondents.

Tony Gallagher

Mr Gallagher said the attacks on Mr Gove were politically motivated.

"It wouldn't take too much of a cynic to assume part of the reason for (the apparent smear campaign) is to remove him as a leading light of the Leave campaign," he said.