Green’s Dictionary of Slang

(UK black) a large stereo tape recorder-cum-radio carried by youths.

1999		(con. 1979–80) A. Wheatle Brixton Rock (2004) 21: A battered suitcase thumped out Dennis Brown’s Money in My Pocket. [Ibid.] 75: I’ve got this wicked Brixton suitcase, brand spanking.
2001		(con. 1981) A. Wheatle East of Acre Lane 75: A Brixton suitcase thumped out Horace Andy’s ‘Natty Dread Ah Weh She Want’. [Ibid.] 141: John Lee Hooker’s ‘One Bourbon, One Scotch, One Beer’ played from a suitcase.
2004		(con. 1990s) N. ‘Razor’ Smith A Few Kind Words and a Loaded Gun 360: Local youths, all baggy trousers, baseball caps and bad attitude. Their huge stereo, known locally as a ‘Brixton briefcase’, was on the ground at their feet, pumping out Niggaz With Attitude.