In a career spanning 45 years, Barson came to prominence in the late 1970s as the keyboard player for the band Madness.

After reading about the emerging New York graffiti scene, they spray-painted their nicknames ("Mr B" and "Kix") along with two friends' names "Cat" and "Columbo" around north London.

Two years later, Madness disbanded, but Barson did join them for the recording of their final single, "(Waiting For) The Ghost Train".

Both Barson and his bandmate, Suggs, have contributed to Audio Bullys' album Higher Than the Eiffel.

In September 2016, Barson told the website The Canary that he was a member of the left-wing campaigning group Momentum and voted for Jeremy Corbyn in the Labour Party leadership election.