The Cabs, of course, did not arrive at “Nag Nag Nag” out of the blue, and this comprehensive, for-fans-only box documents the five years it took them to get there. CD1 (’74/5) is doodling, with simple loop experiments (“Exhaust”) between occasionally arresting nods towards pop (“Stolen From Spectra”) and disturbing newspaper cut-ups (“She’s Black”). CD2 (’76/7) is the real revelation: a sequence of quietly disturbed tone poems which presage the Aphex Twin’s Selected Ambient Works Vol 2. CD3 (’77/8) presents a more familiar picture, with primitive prototypes of Cabs standards like “Baader Meinhof” and “Nag Nag Nag” itself.