I don’t mean to suggest “Let England Shake” is anything other than excellent, but I can’t help thinking that one supplementary reason why PJ Harvey’s latest album has had such laudatory reviews (better, mostly, than the equally good “White Chalk”) is that offers journalists so much to write about. “Let England Shake” is so full of imagery, content, allusion, it offers up boundless possibilities of meaning. Reductively, it has been called a protest album. Expansively, you can parse (or, maybe, project on) it for all manner of ideas about war and nationality.