In his short life while battling cancer, he made bracelets to help fund cancer research through a charity movement called, "Help Harry Help Others." He was voted Britain's Kindest Kid in 2009 for his fundraising campaign to raise cancer awareness.

Harry Moseley, 11, had been in a coma at Birmingham Children's Hospital since Aug. 10 after the tumour in his brain grew by 50 percent and required major brain surgery that sent him to a coma state.

"He singlehandedly raised over £85,000 for brain cancer research by fundraising and selling hand-made bracelets... He also helped Cancer Research UK raise hundreds of thousands of pounds by supporting our work and speaking about his illness at events," said Richard Taylor, executive director of fundraising and marketing at Cancer Research UK.

Harry's mother Georgina is devastated by his death.

"My brave inspirational boy fell asleep in my arms at 11.10pm. Suddenly our world is a very dark and cruel place," she posted on Harry's Twitter account Sunday morning.

"I have lost my baby, best friend and hero very quickly and my life will be very empty moving forward," she told SkyNews.

On the official Web site of Help Harry Help Others, Taylor said, "It was Harry's wish that the whole of the UK would wear one of his bracelets with pride... Harry was a very special boy - even when faced with a life-threatening illness he retained his cheeky persona and his drive to help others. He truly touched the hearts of everyone that he met and the difference he made during his short life is remarkable."

Reports say Prime Minister David Cameron has been seen wearing one of Harry's bracelets. Actress Amanda Holden is also a known supporter of Harry's efforts.