Clive Burr passed away in his sleep on March 12, 2013. He was 56.
Burr joined Iron Maiden in 1979, and was brought in by then-guitarist Dennis Stratton. He stayed for three albums and departed in 1982. After that he worked on several projects through the 90s but never officially joined any band.
Burr has since been diagnosed with multiple sclerosis, the treatment of which left him deeply in debt. Iron Maiden staged a series of charity concerts and were involved in the founding of the Clive Burr MS Trust Fund. Burr had to use a wheelchair because of the MS. More recently Burr became patron of the charity Clive Aid, a charity formed in 2004. Clive Aid has since continued to raise awareness and funds for various Cancer and Multiple Sclerosis (MS) programs around the world through the staging of rock events.
From the Wiki.