When is a party at the Palace not a party at the Palace?

The trouble with inviting famous celebrities to private events is that famous celebrities often post their pictures in very un-private spaces.

Such has been the difficulty for the Duke of York after David Beckham decided to put his daughter's sixth birthday party pictures on Instagram.

Nothing wrong with that you might well say, but Harper Beckham had her party in the kind of place you don't often get to have parties: Buckingham Palace.

And that is Buckingham Palace, official London residence of HM Queen - not Beckingham Palace, the one time residence of the Beckham family in Hertforshire that was often nicknamed so.

It turns out Harper Beckham - the fourth child of David and Victoria - lived out her princess fantasy from the Disney film Frozen in Buckingham Palace last week.

Harper is pictured on her father's Instagram account with friends and a "real" princess, the daughter of the Duke of York, Princess Eugenie.

So is Buckingham Palace suddenly available to any six year old who fancies realising her Frozen fantasy in an actual palace?

Sadly no.

A spokesman for Buckingham Palace, who referred to the event as a "tea", told ITV News that this was a private engagement.

Members of the Royal Family who live at Buckingham Palace - by which the official meant Prince Andrew - are entitled to invite people to the grounds in a private capacity.

The official was also very clear that any refreshments that were made available to the Beckhams for this "tea" were paid for privately - not from Royal Family expenses.

David Beckham with his mother and daughter outside the palace. Credit: David Beckham/Instagram

Seeing the potential criticism coming his way over the Palace giving preferential treatment to the Duke's millionaire friends, David Beckham defended the party location writing: "One last picture of the birthday girl....Just to be clear this wasn't the palace opening the gates for Harper's birthday party, this was a tea party where us and other guests were invited so it was a beautiful thing to do with my mum, Harper plus a few school friends...We were honored to be able to there...Beautiful tea party..."

So to be clear, this was not a princess party at the Palace for the daughter of a very famous footballer put on by one of the Queen's sons for his rich friend.

It was a private tea, paid for from private funds, for some private guests of a Prince who happens to reside at Buckingham Palace.

Just so we have got that clear...