From the cruel metaphor of the opening “Iron Lung” to the weary conclusion of “Devil’s Song,” Bonk is one angry record. Although technically an Australian group, Big Pig began in London around 1985, and hatred of Margaret Thatcher’s England seems to fuel the bittersweet material. Lead singer Sherine has a dark alto that complements the songs’ often depressing tone. But vocals aren’t the half of Big Pig. The instrumentation is keyboards, harmonica and drums — lots of drums, played by three out of seven members. The trundling, tribal rhythms give the songs the effect of steamrollers extinguishing their protagonists’ burned-out lives. Sparse musical textures, including group chants and that anomalous bluesy harmonica, help make Bonk compelling listening. Big Pig’s obviously got attitude to burn, and who couldn’t use a healthy blast of protest?