The heartfelt letter read:
Dear Daphne,
My wife and I send our warmest wishes to you on the occasion of your 99th birthday on Friday.
We hope you have a wonderful celebration surrounded by family and friends and that you've managed to escape hospital. Congratulations on reaching this important and impressive milestone before your centenary year next year.
Happy birthday, Daphne.
Best wishes,
Harry and Meghan, the Duke and Duchess of Sussex
Daphne's daughter Michelle Haywood told Today that a friend contacted Harry and he replied overnight and they were 'so excited' about the letter.