Stella McCartney has donated a signed sketch to an art auction held each year by the Special Yoga Centre, which provides yoga therapy and other support to children with cerebal palsy, Down's syndrome and epilepsy.

McCartney has supplied the centre - whose honorary patrons include Samantha Cameron and Trudie Styler - with children's clothes for several years. The auction, also featuring works by David Hockney, Gavin Turk and Damien Hirst, takes place May 15 (see Diary).