After his late 2000s double whammy of Prodigal Son and True Stories revitalized his lengthy career, British folk singer/songwriter Martin Simpson's 18th solo studio album, Purpose & Grace, could be seen as a step backwards, having only put pen to paper himself twice on its 13 tracks. But joined by an impressive who's-who of traditional British folk, its eclectic array of songs, spanning from the 17th century (Scottish ballad "Barbry Allen") right up to the mid-'90s (Bruce Springsteen's The Ghost of Tom Joad outtake, "Brothers Under the Bridge"), ensures that it's no ordinary covers album. The likes of the June Tabor duet, "A Strange Affair," is an emotive update of the Richard Thompson classic they performed together on her 1980 album, A Cut Above, and a country-tinged reworking of Irish folk song "The Lakes of Ponchartrain" (which previously appeared on 1985's Sad or High Kicking) may already be familiar to longtime fans. But elsewhere, Simpson uses this opportunity to breathe new life into the likes of "Little Liza Jane," turning the New Orleans brass band standard into a feel-good, steel guitar-led hoedown, Yip Harburg's Great Depression-era classic "Brother Can You Spare a Dime," which is transformed into a stripped-back slice of melancholic blues featuring the dulcet tones of Glaswegian protest singer Dick Gaughan, and traditional number "Bad Girl's Lament," which is given a haunting air thanks to the ethereal vocals of Fay Hield and the mournful fiddle of Jon Boden. The two new compositions, the jaunty banjo-plucking tributes to the late Kentucky musician Banjo Bill Cornett ("Banjo Bill") and folk singer Mike Waterson ("Don't Leave Your Banjo in the Shed Mr. Waterson") fit comfortably next to the more established material, but it's the respectful but inventive interpretations which prove that Simpson's purple patch shows no signs of abating just yet.