Hidden Seam (Lisa Knapp), 20 (Kate Rusby)

WHILE both bask in the embers of the British folk boom, Lisa Knapp and Kate Rusby are poles apart.

20 by Kate Rusby.

WHILE both bask in the embers of the British folk boom, Lisa Knapp and Kate Rusby are poles apart.

With 20,Rusby, one of the revival's senior figures, continues a conservative approach that has characterised her previous albums. In style, she aligns to the right of Fay Hield, Emily Portman and the Unthank sisters.

Knapp occupies a niche at the opposite end of the spectrum, alongside mavericks Eliza Carthy, Martha Tilston and Mary Hampton. Hidden Seam matches the free-ranging promise of her 2007 debut, Wild and Undaunted. Knapp's originality, displayed in inventive self-penned, trad-influenced songs, and her uninhibited singing bring to mind artists Bjork and Ani DiFranco.

By contrast, Rusby's self-compositions are so fastidiously and steadfastly informed by tradition, they could be satirical. Her anniversary album does scant justice to a score of stellar guests, who are consigned to perfunctory support roles as Rusby revisits 20 old favourites from her two-decade career.

Knapp uses her contributors imaginatively, most notably singers James Yorkston-Marry Waterson and Alasdair Roberts in the striking vocal round sections of Black Horse and Hunt the Hare; likewise Kathryn Williams's sweet harmony on the less ambitious Hushabye. Martin Carthy's idiosyncratic guitar phrasing fits Two Ravens, a dark song that metaphorically alludes to Alzheimer's disease, to a T. Zi Lan's guzheng (zither) adds a Chinese air to the breezier Ruler of the Rest. Elsewhere, the unorthodox percussion work of Bellowhead's Pete Flood provides a robust pulse. Knapp's multi-instrumentalist producer and husband Gerry Diver leaves light fingerprints all over the set: autoharp and glockenspiel here, pedal steel and recorders there, plus keyboards and programming.

Rusby's co-producer and partner Damien O'Kane is similarly ubiquitous yet unobtrusive, contributing exemplary guitar work as second fiddle to mandolin maestro Chris Thile (on Awkward Annie), dobro master Jerry Douglas (Sho Heen) and Richard Thompson's incomparable electric guitar playing plus the drumming of Radiohead's Phil Selway (Who Will Sing Me Lullabies). Rusby's vocal duets with her male guests, Thile and Thompson on the aforementioned tracks, a harmonising Bob Fox on Annan Waters, a quietly passionate Nic Jones on The Lark, a powerful Dick Gaughan on the jaunty brass-enhanced Jolly Plough Boys and, most unexpectedly, Paul Weller on Sun Grazers hold sway. Paul Brady, Jim Causley and Dave Burland's parts are curiously restrained. The female contributors, save Eddi Reader (Wandering Soul), are comparatively mute, the singing of Sara Watkins, Mary Chapin Carpenter, Aoife O'Donovan and Sarah Jarosz disappointingly subservient to Rusby's tender but ultimately tedious monotone lead.

Knapp's vocals are contrastingly freewheeling, soaring and gyrating with gymnastic athleticism.

Hidden Seam rating: 4 stars

20 rating: 2.5 stars