Prince Harry and his brother, Prince William, the Duke and Duchess of Cambridge’s children were reportedly invited to Frogmore Cottage to celebrate Lilibet’s first birthday party.William and Harry were reported to have fallen out at the end of 2018, and the party invitation was apparently intended as an “olive branch”. But, says a royal source, William and his wife Kate Middleton had a previous engagement – a special visit to Cardiff Castle to mark Her Majesty the Queen’s Platinum Jubilee.