The Duke of Cambridge will host his first investiture ceremony later as the scope of his royal duties widens.
The Duke has recently given up operational duties with the RAF after serving three years as a search and rescue helicopter pilot in North Wales.
He is now in a "transitional" year, sources have said, and is considering options for his "public service".
More top news
Weather: Heavy rain and strong winds in the north
His representatives said Cassidy, who was hospitalised last week, died "surrounded by those he loved."
The company’s recently appointed Chief Executive Dara Khosrowshahi said the breach was made by two individuals outside the company.