Keith Emerson and Greg Lake met in December 1969 when Emerson's band, The Nice, and Lake's band, King Crimson, were billed together for a series of concerts at the Fillmore West in San Francisco. Emerson was looking to form a new band, and Lake wished to leave King Crimson. During a soundcheck before one of the shows, Emerson described the first time he and Lake played together: "Greg was moving a bass line and I played the piano in back and Zap! It was there." The pair had met twice before in England: in 1969, when the Nice and King Crimson performed at the Jazz and Blues Pop Festival in Plumpton; and at Fairfield Halls in Croydon.