Queen Camilla’s polite attempt at breaking the royal protocol was blocked by her sister-in-law, Princess Anne, during a royal engagement this week.The pair attended a joint engagement at the University of London’s Foundation Day Wednesday.As chancellor, the Princess Royal, 74, presented Camilla with an honorary doctorate of literature certificate as a sweet nod to her ongoing efforts in promoting literature in the UK.After the pair arrived together at the university, they were escorted into the Senate House, where the ceremony took place.But to show respect to Anne, Camilla invited her to enter the room first — breaking the first step of the royal protocol that has been in place since 1066.Anne, who is all too familiar with the royal family’s order of precedence, “smiled and politely refused” — instead welcoming Camilla to enter the room first, the Express reports.During public-facing duties, royals are expected to respect the “sequential hierarchy of nominal importance” — meaning that Their Majesties are to always enter the room first.And while Anne, who is the only daughter of the late Queen Elizabeth II and Prince Philip, was born into royalty, she still ranks below King Charles’s wife within the Firm.Camilla, 77, and Anne have grown close since Her Majesty joined the royal family in 2005 following her wedding to Charles, 76.At Wednesday’s event, the duo were seen exchanging laughs and posing for photos together, as they joined four other recipients of honorary doctorates at the university.Just days after the outing, Camilla was forced to pull the plug on her appearance at the Royal Variety Performance following a chest infection that she’s been battling for the better part of this month.Camilla missed Friday night’s glitzy event, held at the Royal Albert Hall in London, to nurse her ongoing infection, the palace said.Morning Report and Evening Update: Your source for today's top stories Please provide a val...