Complex sentence: Jack Hayter first made a mark in the UK with the Alt.Country group Spongefinger who released two well received albums but only really came into prominence when he joined Hefner with whom he recorded and released several albums, singles and EPs for the Too Pure label.
Split into simpler sentences: Jack Hayter first made a mark in the UK with the Alt.Country group Spongefinger who released two well received albums but he only really came into prominence when he joined Hefner. In Hefner, Hayter recorded and released several albums, singles and EPs for the Too Pure label.