What did he do?
The veteran newsreader was asked to be patron of the charity’s Caterpillar Appeal, which aimed to raise £4m to refurbish Naomi House, near Winchester in Hampshire.
The charity approached Stewart in 2014 to be patron of the Caterpillar Appeal because it needed a figurehead with gravitas and passion for the cause. He already had an association with the charity but had until that point remained largely on the periphery, the charity says.
Stewart threw himself into supporting the appeal and attended all its key moments, from speaking at length about the charity’s work at its press launch to climbing the 30-foot scaffolding to place the final roof tile at the refurbished hospice’s topping-out ceremony.
The charity said new supporters emerged throughout the appeal with the same story to tell: "Alastair said we should get in touch."
He tirelessly encouraged his media contacts to retain interest in the story and his efforts led to the parliamentary press gallery supporting the cause.
The charity said he also spent considerable amounts of time with the children, young people and families that it cares for, including spending more than an hour with a boy receiving end-of-life care from the charity.
The appeal ended up receiving more than 10,000 donations to hit its target and the new Naomi House opened in September last year.
The charity said that without Stewart’s support it would have taken longer to raise the funds it needed and it might have had to complete the work to a lower specification.
He has since accepted a permanent role as patron of Naomi House and Jacksplace.
What did the judges say?
Niamh Paul, celebrity liaison manager at the Teenage Cancer Trust, said Stewart was "just the sort of supporter every charity is after" and Naomi House had built a long-term, meaningful relationship with him.
"Amazing to see the incredible impact Alastair has had on the fundraising for the rebuild of Naomi House Children's Hospice," she said. "It is fantastic that he has been involved right through the process and that not only has he given of his own time so generously but he has also encouraged his contacts to support it too."
Alex Feis-Bryce, chief executive of National Ugly Mugs, said: "Every charity needs an Alastair."
Mathew Bose, the Encephalitis Society
David Gandy, Battersea Dogs & Cats Home
Fred Sirieix, DM Thomas Foundation for Young People