The small group was seen at the landmark in a Facebook Live video on Tuesday (17 August) afternoon, with Police Scotland confirming officers were still in attendance hours later.
But just why have they attempted to take over the historic castle? Is there any legal right for them to do so? And what are some of the bizarre theories they are claiming to be true?
Here is everything you need to know.
Why have they ‘seized’ the castle?
In the 13-minute Facebook Live video, a woman says the castle “belongs to the people” and that they are “taking our power back”.
She adds the Scottish people have been “lied to all our lives” and that the “building belongs to us, we have taken the castle back” in an effort to “restore the rule of law”.
Another man then says: “Treason’s been going on for that long now, we can’t sit back and let everybody perish under the stupid legislation and fraudulent government tyranny, so let’s just take it all back, not just the castle.”
The woman then speaks again, calling for “no more enslavement” and the “people and commonwealth are going to be free”.
She tells viewers they are going to “take everybody down”, including the government, the courts and “the crown is coming down today”.
After saying the group is “putting we, the people, back into power”, a second man adds: “We are the people.”
What is the Magna Carta?
As police appear, she shouts “notice to compel” and informs officers they are seizing the castle under article 61 of Magna Carta – “the only law in the land”.
But since the Magna Carta predates the Act of Union by about 500 years, it only applies to England, and has no relevance to the laws of Scotland.
The Magna Carta - signed by King John in Surrey in 1215 - was a document made up of 63 clauses which sought to reform English law and move society on from the feudal system of rule in which the King's word was law.
Clause 61 of the document says the king must adhere to the Magna Carta’s rules, and that under any transgressions, his castles and lands could be seized by a council of 25 barons created to oversee his adherence.
It would appear as if these staunch nationalists believe their government has failed to protect the freedoms and interests of its citizens, and so are evoking the clause as a legally protected way to hold it to account.
However, not only does the Magna Carta only apply in England, only four of its original 63 clauses are still recognised in law - and clause 61 is not one of them.
Over 800 years later, the Magna Carta still ensures that no one is above the law (not even the king), everyone has a right to a fair trial, and there can be no taxation without representation.
Who owns the castle?
Thought the castle is owned by the Scottish Government and the Ministry of Defence, it in the care of Historic Environment Scotland, an executive non-departmental public body responsible for caring for and promoting Scotland's historic environment.
What are the protesters claiming?
The woman in the video also claims “corrupt, evil, satanic paedophiles are running this country” and Scots have been kept “like peasants for 800 years”.
The woman says she has put Police Scotland Chief Constable Iain Livingstone “on notice” about them taking the castle.
One officer asks the woman for her name, to which she says she is “not obliged” to do, before identifying herself anyway.
The police constable then asks: “How many more people are you expecting to come to Edinburgh Castle today to join your protest?”
When she tells him “it’s not a protest, we’re actually taking it back” he replies: “Right, no worries.”
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