Over her 70-year reign, the Queen has met many world leaders from prime ministers to presidents - and even other monarchs.
And before meeting each one, it is said she receives briefing notes, advising her on their personalities and topics she should probably avoid talking to them about.
But when she was due to meet up with Queen Margrethe of Denmark, one royal author has claimed she advised her to steer clear of mentioning on very peculiar topic.
According to royal biographer Robert Hardman, when the two women met for a chat in 1974, she was warned not to mention Denmark's "reputation as the pornography capital of Europe" due to Danes' sensitivity on the issue.
Mr Hardman told the Daily Mail's Chalke Valley History Festival: "Whenever she’s meeting any world leader there’s always two files she studies very closely.
"One is called 'personality notes' and the other 'topics to be avoided'. They don’t hold back, either."
However, he added: "I think two queens are fairly unlikely to stray into that territory."
Today, the Queen has travelled to Scotland with other members of the royal family for their annual week of engagements in the country.
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The monarch, 96, was in Edinburgh for the historic Ceremony of the Keys – the traditional opener to Holyrood week for the Royals - accompanied by her youngest son Prince Edward and wife Sophie Wessex.
For the event, the beaming head of state opted for a lilac look and stood with her walking stick as she was presented with flowers and the keys to the city.
It is the first public duty she has carried out since appearing on the Buckingham Palace balcony for the finale of her Platinum Jubilee celebrations just over three weeks ago.
She only took part in the private parts of Garter Day at Windsor two weeks ago and did not make any appearances at Royal Ascot.
However, pictures were released last week after she met with the Archbishop of Canterbury and the governor of New South Wales at Windsor Castle.
The ancient Ceremony of the Keys takes place on the forecourt of the Palace of Holyroodhouse as part of Holyrood Week – also known as Royal Week – each summer.
It was reported last week that the monarch, 96, who has been suffering from ongoing mobility issues, is planning to be in residence at the Palace of Holyroodhouse in Edinburgh all week.
However, it is thought she will now see how she feels each day before deciding if she will stay at the Palace of Holyroodhouse all week, as normal, and undertake further duties.
