The Royal Family is a global institution and everyone from the King to The Princess of Wales is expected to follow protocol - but exceptions can and have been made.
Prince Philip, Duke of Edinburgh was renowned for his no nonsense approach to royal duties. While there are countless examples to choose from, one story from 2016 highlights this attitude.
The Queen was greeted by President Barack Obama and First Lady Michelle Obama in 2016 when they travelled to Windsor Castle for lunch in celebration of her 90th birthday.