Emerson, Lake & Palmer, also known as ELP, are an English progressive rock super group. They found success in the 1970s and sold over forty million albums and headlined large stadium concerts - one of the largest at California Jam (Cal Jam) in 1974 was in front of 200,000 people. The band consists of Keith Emerson (keyboards), Greg Lake (bass guitar, vocals, guitar) and Carl Palmer (drums, percussion). They are one of the most commercially successful progressive rock bands and from the outset focused on combining classical pieces with rock music. The legendary Rock Band reunited to celebrate their 40th Anniversary and headlined London's first High Voltage Rock Festival. This was the historic moment when Emerson Lake and Palmer performed for the first time since 1998.