Prince Philip memorial: Why Kate Middleton and William arrived after Charles and Camilla?

Prince William and his wife Kate Middleton's arrival at the memorial service for Prince Philip after Prince Charles and Duchess Camilla has sparked a debate online.

As royal fans and experts discussed the event a user asked, "Do we know why The Duke and Duchess of Cambridge arrived after Prince Charles and Camilla?"

The user said, "There must be a reason otherwise they always arrive before C&C as per the order."

Royal expert Angela Levin, who seemed to have no answer, said it was "Good point. We would like to know".

Marlene Koinig, an expert on the British and European royalty, said "could be any reason. At the Diamond Jubilee the queen and Philip got caught in traffic and arrived late."

A user said, "Prince Louis was mentioned in the CC and ended up not attending. I wonder if he was sick etc and they just ran late?"

Another said, "He was down as TBC though. He is still only 3 - suspect they decided in the end it would be too much for him."