After leaving school at sixteen Al played guitar and sang in various bands including Three Minute Warning, Four Minds Crack and then The Wall (produced by  Steve Jones of the Sex Pistols,  Jimmy Pursey of   Sham 69 and Pete Wilson producer of The Jam/Sham 69). He appeared in music magazines like  Melody Maker, Sounds and NME and recorded guitar on The Wall's Day Tripper 12" and 7" EP, recorded at Crass' Southern Studios in 1982, and continued performing live and on tour until late 1983. The Wall reformed in 2007 and appeared twice at the Rebellion punk festival in Blackpool and on further UK tours.

From 1997 to 2006 Al was the lead guitarist for rock singer Caroline Alexander (Organic/Universal), who was produced by Ace (Skunk Anansie), Roger Tebbutt (King Prawn) and Dave Lynch (Toploader). Alongside extensive recording work, he frequently appeared live on UK tours, including headlining The Forum and supporting Girlschool at the London Astoria in 2005/6. 

In 2006 Al collaborated with the singer Rashid Ali for a Sky TV show 'The Boland Show' which had interviews with celebrities and incidental music and intros performed by Al, Rashid and backing singer Sasha. Al and rashid then went on to record an album Rip it Up (Ankh Music) which had some recordings produced by Tim Mcfall Snow Patrol. 

2008-9 Al collaborated with David Schaal on the show Reality Chokes. He also co-wrote and composed the original music for the production and appeared as one of the main characters Dan, both in London and at the Edinburgh Festival in 2008/9, garnering some five star reviews and a nomination for the MTMUK awards.

From 2010-17 Al played guitar in punk tribute band The Clones and also appeared live occasionally with the band Goon Squad.

In 2016, Al re-appeared with The Wall at the 40th anniversary Rebellion Punk festival at the Opera House, Winter Gardens, Blackpool, and also appeared with the band live on their UK tour, co headlining with Spizz Energi in 2017 as well as recording new material. In February 2022, the four track 'Back to the Wall - Manchuria' EP by The Wall was released by Spectacle Music, featuring two previously unreleased Wall songs written by Ian Lowery and two new songs written by Al Gregg, as a tribute to both Ian Lowery and Andy Griffiths. The EP received fantastic reviews from the likes of Louder than War and Phonotonal and received regular radio play.