WHAT IT IS: A national charity that aims to "create joy through live music" and improve the quality of life for adults and children with illness and disability
WHAT IT DOES: Performs live concerts at hospitals, hospices, daycare centres, special needs schools and nursing homes
HOW IT'S FUNDED: Fees from hospitals and homes, grants, donations, the Department of Health, the Big Lottery Fund and GlaxoSmithKline
The sun is blazing across the Thames, sneaking through the drawn blinds and into the elderly acute patients' ward at Guy's Hospital. In a bay flanked by signs warning of a gastroenteritis outbreak, someone is singing.
"The sun has got his hat on, hip hip hip hooray," pipes Stacey-Jane Douglas, one of Music in Hospitals' 300 musicians.
Douglas swings her guitar from bed to bed, serenading each patient with old favourites such as Daisy Daisy and Sweet Molly Malone. Then, as a cleaner pulls her J-cloth across the bedposts, she launches into These Foolish Things.
A frail but elegant woman lies on the bed, eyes transfixed and smiling.
"How often do you come here?" she asks. "I've never heard of you before.
It hasn't taken her mind off her illness, she says - she came in the night before with a suspected heart attack. But she tells Douglas: "It's amazing you've taken the trouble to set it up."
Later, she fishes in her handbag and apologises for not having any change to give the musician. "I had to come here very suddenly, you see," she says.
Another patient starts singing along. "It's lovely to hear good music," she says. "Not like that rubbish they put on the radio."
And it's not just the patients who benefit. Sam Woods, the ward manager, says the staff love it too. "It brings an air of calm and tranquillity to the ward," she says.
The charity, which was formed in 1948, now hosts some 4,000 live concerts across the UK each year. It pays the musicians a nominal fee and expenses, and gets some payment from host healthcare centres. But it still needs to make up the shortfall from grants and donations - demand for its service is growing all the time.
Music in Hospitals works on the principle that music can enhance immune system function and promote rehabilitation and recovery. The charity chooses its performers for their high standards of musicianship, breadth of repertoire and communication skills. Performances range from string quartets to old-time music hall, but they are usually small to retain intimacy with the patients.
Diana Greenman, the charity's chief executive, says: "The challenge now is to raise as much money as possible so we can make concerts free of charge and reach many more people."