A decade ago, three of the finest voices in Americana got together to make a sublime supergroup record. Case/Lang/Veirs, in case the title didn’t make it plain, brought together Neko Case of the New Pornographers, stalwart Portland songwriter Laura Veirs and kd lang, the Grammy-winning Canadian country icon. Sadly, that glorious album has remained a one-off – though a new anniversary release includes a gorgeous never-before-heard song, Accidental Tattoo – but happily, lang is joining the Guardian for a very rare interview to answer your questions.