Much has changed for Rachel and Becky Unthank since 2007′s The Bairns but they are still prone to a bitter tragedy. Rachel Unthank & The Winterset, then an experimental curiosity in a divided folk scene, were propelled to widespread attention and acclaim by a Mercury Prize nomination but Belinda O’Hooley, key to much of that record’s eerie, piano-driven thrust, departed in difficult circumstances. A new name and different direction followed but from the opening bars of a commanding first track, Last sees The Unthanks returning to their spectral piano forte.

In this sense, the new record is perhaps a more natural successor to The Bairns than 2009′s Here’s The Tender Coming, on which the finest moments came from elegant string arrangements (still playing second fiddle to the sisters’ lead vocals). Swapping studio for farmhouse, Last is sparse and shrouded but also swirling and sweeping. Moorland opener ‘Gan to the Kye’ (one of a few traditional Northumbrian songs included) feels bracing and breathtaking, like keeping a grim, windswept watch over surging grey surf. As elsewhere, the atmosphere shifts from fragile and ghostly to stately and stirring, bleakness unfolding as expansively as expressively, with a splendid synthesis of piano and strings supporting the sisters’ dominating, elevating, unconventional harmonies. “Disappointment is everywhere”, they chant on a Jon Redfern cover. Not here.

Despite its mischievous moniker, there is no indication that Last signals the end for The Unthanks, though an unfortunate habit of shedding talented members might prompt extra scrutiny on this point. Adrian McNally’s title track is the one original song included, spotlighting both his ambition and increasing prominence as the band’s guru, producer and replacement pianist. Whether the song itself, tune redolent of Pink Floyd’s ‘Us and Them’, plays central pillar or plodder is debatable but it suffices as a segue from traditional material to the first of two pairs of covers. Versions of Redfern’s ‘Give Away Your Heart’ and the Tom Waits track ‘No One Knows I’m Gone’ impress, the former a lyrical lament rendered raw and the latter a simple string arrangement superbly well-suited to The Unthanks’ oeuvre. Later, a brave attempt at King Crimson’s ‘Starless’ is sober but successful.

Contrasting facets of spectral desolation and august grandeur create a tension that permeates the album, until all comes crashing down on ‘Close the Coalhouse Door’, starting sweetly but descending to a disquieting dirge of blood and bones and bairns at Aberfan. Written by the late Gateshead songwriter and singer Alex Glasgow, the anguish is unmitigated and indelible. A final, fleeting reprise of the title track is a bandage for the broken bodies.

Their latest effort might not win Rachel and Becky many new fans but the album is more than an exercise in honing strengths or recreating the prevailing mizzle of The Bairns. Although it is a pity that no Robert Wyatt or Antony & the Johnsons songs (as featured in well-received Union Chapel shows before Christmas) are included on the record, Last is a worthy addition to The Unthanks’ undeniably impressive canon.