Mila's mother Lynda took to Twitter to praise Kate for sending a 'beautifully' handwritten letter to mark her daughter reaching the end of her treatment.

Lynda shared a heartwarming photo of Mila holding the cherished letter in its envelope with a large smile.

Captioning the snap, Lynda wrote: 'Very grateful to receive a beautiful handwritten letter from @KensingtonRoyal. Such a beautiful keepsake for Mila to look back on for many years to come (content of which will not be disclosed) such a lovely gesture thank you Catherine Duchess of Cambridge.'