In 1969 he began to perform as Cyriel Havermans in live concerts in the Netherlands with members of the nascent Focus (Thijs van Leer, Martijn Dresden, and Hans Cleuver) as his backing band.

Aside from Cyriel's plaintive, wordless wailing on "Pupillae" from the Focus II LP's sidelong "Eruption" suite, his vocal talents found no other outlet on this mostly instrumental album.

He left the band to pursue a solo career playing melodic, acoustic guitar music with English lyrics.

A second album, Mind Wave, followed in 1974, and Cyril's group was sometimes featured as an opening act for Focus' European concerts in 1975.

In October 2016 he was interviewed and sang and played blues tunes on acoustic guitar on the BredaNu television show, On Stage.