Many of the songs contain references to places and hang-outs local to Newport. Much of the humour comes from the adoption of hip-hop style and language, adapted into the local South Wales vernacular, partly to poke fun at "chav culture". Their music also satirises gangsta rap by highlighting the disparity between the band's deliberately unglamorous image, and the media hype and glamour usually associated with gangsta rap. While the correct spelling of the name of the group would require correct punctuation (with an apostrophe at the end of Lookin), no sleeve or band literature indicates one.

The group recorded 6 albums before gaining a major record deal and were signed to the East/West record label, the home of rock band The Darkness. Rumours suggest that GLC was signed after record label bosses heard The Darkness playing GLC tracks whilst on tour (source: BBC Radio 1 - GLC Documentary). GLC went on to support The Darkness in the latter stages of their UK tour.

GLC's first UK chart entry was "Half-Man Half-Machine"/"Self Suicide", which reached the top 40. When group member Dwain Xain Zedong was phoned by BBC chart presenter Wes on the Official Chart Show to be informed of this, Xain informed the rest of the band that they had reached number 1, much to the shock of the DJ. "Half Man Half Machine" was a surreal song about one of the members (Eggsy) believing he was a robot, dressing up in foil, and going to the shops to buy ten fags and some crisps. The song namechecks many well-known 1980s 8-bit computer systems including Binatone, ZX Spectrum, Commodore 64, ZX81 and BBC Micro.

In August 2004, the group reached number 3 in the UK singles chart with "Guns Don't Kill People, Rappers Do". With the tagline "The gun is the tool, the mind is the weapon", this track - again satirising the American hip hop scene - was a popular radio hit. The B-side was album track "Soapbar".

Their first nationally-released album was called Greatest Hits, the name a play on both the group's previous lack of commercial success and their "stoner" image; it compiled a mixture of new material and selections from their previous six unofficial albums. It was released in September 2004, and debuted at number 5 in the UK Album Chart. This album was released in May 2005 in the USA with the title "Straight Outta Newport" with cover art similar to NWA's album Straight Outta Compton. However, this version of the album was missing two tracks - "Maggot" and "You Knows I Loves You".

Their next single release was "Your Mother's Got a Penis", with an accompanying video based on a supermarket theme. "Your Mother's Got a Penis" first appeared on their album The Manifesto, and reached #14 in the UK. This song is based on a sample of Greg Philinganes' track "Behind The Mask" (originally by the Yellow Magic Orchestra and later covered by Eric Clapton in 1987).

The band - informally known as "the Chain" or simply "the GLC" - released, "You Knows I Loves You", a parody of 1980s love songs from the albums Greatest Hits and The Manifesto, on 13 December 2004; this reached number 22 in the UK chart. "Your Missus Is A Nutter" is the first single from second album Safe As Fuck. The album was originally going to be called "Safety In Numbers", a tribute to the album Power in Numbers by alternative L.A. rap group Jurassic 5. The single reached #14 in the UK. They dedicated the song to Victoria Beckham, which resulted in them being summoned by the Newport mayor's office, who also objected to the title of their album, Safe as Fuck.

In a further controversial incident in 2005, GLC were invited by the Football Association of Wales to perform before the World Cup qualifying match against England at Cardiff's Millennium Stadium. Perhaps unsurprisingly, given the nature of the band's music and the participation of England star David Beckham, the band dedicated "Your Missus Is a Nutter" to the footballer about his wife, who was present at the match. The ensuing furore, with the Welsh football authorities having to apologise to the Beckhams (despite David Beckham appearing to take the joke in good humour) as well as expressing outrage at the band's perceived lack of respect, prompted many people to question exactly why the organisers had hired them to play in the first place. In January 2009, GLC appeared on This Feeling TV, and revealed more about the incident.

In January 2006, Maggot appeared on Celebrity Big Brother in the UK. He finished in third place behind Michael Barrymore and the non-celebrity Chantelle Houghton.

In 2005, Eggsy appeared on a special music edition of Celebrity Weakest Link, and proved himself to be quite astute despite his stoner image, finishing second to eventual winner Fish (born Derek William Dick, formerly of Marillion).