The hereditary peerage system in the UK currently favours male primogeniture, which could affect any potential children that Hugh Grosvenor, 7th Duke of Westminster and Olivia Henson have in future.
The Duke and Duchess of Edinburgh did not appear at the Buckingham Palace garden party with their cousins, Prince William, Princess Beatrice, Princess Eugenie, Peter Phillips and Zara Tindall on Tuesday
The Duke and Duchess of Edinburgh's daughter Lady Louise Windsor was notably absent from the royal family's Easter Sunday gathering at Windsor Castle this year – find out why