The film, titled Royal Family, followed the royals around for an entire year including scenes of breakfast time inside Buckingham Palace as well as the Queen’s visits to Chile and Brazil.
It was aired on the BBC and ITV in 1969 and it was watched by around 37 million people.
But some were horrified to discover intimate details which showed the Queen mucking in following trends of every day people.
It is understood some of the personal aspects that horrified viewers at the time would be seen as trivial today.
One example was when the Queen was seen to store food in Tupperware containers.
The Queen and her advisers then “realised that being too normal was as dangerous as being too different,” according to the Smithsonian Channel which recently uploaded a clip from the documentary on YouTube.
The Queen decided the documentary was too intrusive and it is said she ordered the film to locked into BBC vaults, never to be seen in its entirety again.
Princess Anne notoriously hated the documentary, later saying, “I never liked the idea of ‘Royal Family’, I thought it was a rotten idea.
“The attention which had been brought upon one ever since one was a child, you just didn’t need any more.”
Meanwhile one Royal biographer said the Queen regretted her decision to allow the cameras in and it came to be seen as a “reinvention that went wrong”.
The documentary may have been shut in the vaults of the BBC, but short clips have emerged in recent years.
In 2011 the Queen granted permission for the National Portrait Gallery to play a small extract as part of an exhibition celebrating her Diamond Jubilee at the National Portrait Gallery.
The 90 second clip shows the Queen sitting down to breakfast at Buckingham Palace with Prince Philip, Prince Charles and Princess Anne and tell them an anecdote about a dignitary falling over in front of Queen Victoria.
And later that year additional clips were also shown as part of the BBC documentary The Duke at 90 in 2011, celebrating Prince Philip’s 90th birthday.
Paul Moorhouse, the National Portrait Gallery’s exhibition curator at the time, said: “Legend has it that the Queen doesn’t want parts of it to be shown.
“Regrettably, the film hasn’t been seen for a long time. It just disappeared. There is a reluctance for this to be revisited.
“I wish we could show it in its entirety. It tells you a lot about family life. And it redefined the nation’s view of the Queen – the audience were amazed to be able to hear the Queen speaking spontaneously, and to see her in a domestic setting.”
Express.co.uk has contacted Buckingham Palace for comment.