The Sun today defended its "cast iron right" to publish 80-year-old images of the Queen giving a Nazi salute as a child.
And it called on the Royal family to "wake up" rather than go on the "defensive" about the front page story from Saturday.
In a leader today, The Sun said: "Our Royals’ popularity is soaring. Yet they are still surrounded by stuffy and out-of-touch courtiers for whom secrecy is paramount.
"We knew our pictures of the Queen giving a Nazi salute as a child would not harm her reputation in any way.
"Nor should they.
"The Palace were naturally defensive and aggrieved. But they should wake up. As historian Dr Karina Urbach and others said yesterday, those images should have been released long ago…
"Winston Churchill said: 'Those who fail to learn from history are doomed to repeat it.'
"For all our futures, we should know as much detail as we can about our past."
Press Assocation reports that Buckingham Palace is considering taking legal action over the leaked footage that shows the Queen as a child performing a Nazi salute with her family.
The Palace has launched an inquiry into how the 17-second black and white film came into the hands of The Sun.
It shows the Queen, aged six or seven, join the Queen Mother and her uncle Prince Edward in raising an arm in salute as she played alongside her younger sister, Princess Margaret.
A source told PA the royal household is trying to ascertain where the film came from, who it came from and why it was handed over to the newspaper.
A Palace spokesman said: "It is disappointing that film, shot eight decades ago and apparently from Her Majesty's personal family archive, has been obtained and exploited in this manner."
The grainy footage from 1933 shows the Queen playing with a dog on the lawn in the gardens of Balmoral, The Sun claims, before she raises an arm to wave to the camera with Margaret.
The Queen Mother then makes a Nazi salute, and after glancing towards her mother the Queen mimics the gesture.
The Queen Mother repeats the salute, joined by Edward, and Margaret raises her left hand before the two children continue dancing and playing on the grass.
According to The Daily Telegraph, the clip may have been inadvertently released to a documentary maker after a flurry of requests for the unseen royal home movies.
Saturday's Sun front page prompted headlines around the world.
The Sun has a history of running bold front page stories about the Royal Family.
And in 2005 it published a photo of Prince Harry dressed up in Nazi uniform to go to a fancy dress party.