After leaving school at sixteen he played guitar and sang in various punk bands in the early 1980's including Three Minute Warning later Four Minds Crack who hailed from Basingstoke.
He has recently appeared in the films The Real American: Joe McCarthy; Operation Chastity; The Final; Dead Ideas; A Modest Proposal.
He became the narrator voice and up to fifty other characters for the podcast animation series "CodEye", written by Martin Kaluza and Martin Cooper with drawings by Luke Harkus-Jeffries, and has been a brand voice for many companies including; Grundig, DSM, Purina, Floris, Loro Piana, British Airways, Mastercard, Persol, Santander, Chevrolet, Alfa Romeo, Huawei, Sport Pursuit, Jaguar XF, Seat, Fuze Tea, Expedia, Ferrero Rocher, Gucci, Nintendo, Sisal, Fitbit, Pokemon, Garmin, Prudential and Nestle.
Gregg was the lead guitarist for rock singer Caroline Alexander (Organic/Universal) produced by Ace (Skunk Anansie) and also for Rip It Up (Ankh Music).
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 as well as recording new material.
Further musical co-adaptations of Shakespeare, 'Midsummer Night's Scream' (performed at the Dante Hall Theatre, Atlantic City US (2013) and 'Much ado 'bout Nothin' (2014).
Tree later moved to the nearby Her Majesty's Theatre (which was built from his successful Haymarket tenure) and his subsequent establishment of RADA in 1904, with associates included in the Gregg Collection; Henry Ainley, Irene Vanbrugh, Cyril Maude, and Sir Squire Bancroft.