Britain's Catherine, Duchess Of Cambridge Smiles As She Meets Guests During A Garden Party Held At Buckingham Palace, In Central London
Britain's Catherine, Duchess of Cambridge smiles as she meets guests during a garden party held at Buckingham Palace, in central London June 10, 2014. REUTERS/John Stillwell/Pool

Duchess of Cambridge Kate Middleton is mourning the loss of her young penpal, Fabian Bale. The 12-year-old lost his battle with leukaemia on Remembrance Day on Nov. 9. On the day, Middleton and the royal family were commemorating the British fallen soldiers.

"The Duke and Duchess are sad to hear the news and their thoughts are with Fabian's family," a royal spokesperson said in an official statement. The Duchess, who is currently pregnant with her second child, met Fabian in 2011 during her official visit to Royal Marsden Hospital. She later wrote to him a moving letter. The royal couple sent two more letters to him, letting him know that they are tracking his progress.

In the first letter, Middleton wrote to Fabian that she was touched by his "strength of character" and "positive energy," according to Woman's Day magazine. "This must be a troubling time for you, your parents and your sisters, but I know I left the Royal Marsden assured by how incredibly talented, kind and clever the team at the hospital are," she wrote. In her other letters, the Duchess assured him that her thoughts are with him.

Fabian was diagnosed with leukaemia in 2006. He underwent three-years of chemotherapy and went into remission in 2009. However, the disease returned in 2011. His sister Cassie's donated a bone marrow, after which he underwent a transplant procedure.

Middleton had expressed her delight when she came to know that Fabian has found his bone marrow match. She had written in a letter that she hopes to see him in better health after the transplant surgery.

Meanwhile, Fabian's parents Lydia, 53, and Darrell, 52 have told the Mirror that Duchess' letters were a source of strength for their son. Kate's loving letters stayed with Fabian till his soul departed, according to the website's report. Middleton's letters have been buried with Fabian.

Fabian breathed his last at his home in Hampton Court, Surrey, surrounded by his family - his parents, brother Ben, 18, and sisters Oleander, 20, and Cassia, 14. His body was later moved to a hospice instead of a mortuary. Prince William, Duke of Cambridge became the president of the Royal Marsden after his mother Princess Diana's death in 1997.