Born in 1947, Kerr had a background in social work and community development before entering national politics. He was known for his left-wing views within the Labour Party.
He was first elected to the House of Commons in the 1992 general election, representing the constituency of Glasgow Rutherglen. During his time as an MP, he was part of the socialist Campaign Group of Labour MPs. He lost his seat in the 1997 general election to Tommy McAvoy of the Labour and Co-operative Party.
Following his defeat in 1997, Kerr remained active in politics and media. He later joined the Scottish Socialist Party (SSP) and stood as a candidate for them in various elections, including for the Scottish Parliament.