In May 1979, the band signed to GEM Records, a punk rock offshoot of RCA Records. Their first single for GEM, "Stranglehold," was released in June 1979. It was followed by "Tomorrow's Girls" which was released in August 1979. Their debut album, Another Kind of Blues, was released in October 1979 with their second album, Brand New Age following in April 1980. Several EPs were also released in this period and their singles "Teenage" and "Warhead" both made the U.K. charts. Their third album, a live album entitled Crash Course, was recorded at the Rainbow Theatre in London on 30 May 1980 during the Brand New Age tour. Released in 1980, it was their biggest selling album ever. In June 1980, Davies and Slack left the band and were replaced with bassist Alvin Gibbs and drummer Steve Roberts. At this point some of the songs took on a more heavy metal-influenced edge. In February 1981, the band released their fourth album, Diminished Responsibility which was the final U.K. Subs album to chart in the U.K. In April 1981, they released the non-album single "Keep on Running (Til You Burn)", their sixth single for GEM, and the last single by the U.K. Subs to chart in the U.K. It was also their last release on GEM Records as the label folded soon after the release of the single. 1982–1983 The band recorded their next album at the rural Jacobs Studio in Farnham, Surrey in the south of England. Endangered Species was released 19 March 1982 on the band's new label, NEMS, which also folded shortly after the release of the album. Harper and Garratt both consider this album to be the U.K. Sub's best album. Following the recording of the album, Steve Roberts was fired at the end of 1981 and the Subs used both Mal Aisling and John Towe as replacements. The band toured the U.S. in support of the album, hoping to get signed to a U.S. label. It was their second tour of the U.S.; the first occurring in 1979. In July 1982, they became the first Western band to perform in Poland since the imposition of martial law, and the suppression of the trade union Solidarity. Their concert was held in Gdańsk, and they were supported by Brygada Kryzys. In 1983, the band released the three-song Shake Up the City EP on Abstract Records, also recorded at