"How Long" is a 1974 song by the British group Ace from their album Five-A-Side. It reached No. 3 in the US and Canadian charts, and No. 20 in the UK Singles Chart. Although widely interpreted as being about adultery, the song was in fact composed by lead singer Paul Carrack upon discovering that bassist Terry Comer had been secretly working with the Sutherland Brothers and Quiver. Comer returned to Ace in time to play on the song. The guitar solo is by Alan "Bam" King.