Ervine was arrested in November 1974, while an active member of the UVF. He was driving a stolen car containing five pounds of commercial explosives, a detonator and fuse wire.

After 7 months on remand in Crumlin Road Gaol he was found guilty of possession of explosives with intent to endanger life. He was sentenced to 11 years and imprisoned in The Maze.

While in prison, Ervine came under the influence of Gusty Spence who made him question what his struggle was about. Spence's influence unquestionably changed Ervine's direction: after much study and self-analysis, Ervine emerged with the view that change through politics was the only option.