Cambridge Folk Festival | Cherry Hinton Hall, Cambridge

It's becoming almost a tradition for the Cambridge Folk Festival line-up to include the female folky type who now seems to be an annual fixture on the Mercury Prize short list, announced just before the event got away at the weekend. With two previous holders of the office, Eliza Carthy and Kate Rusby, also in attendance, this year it was Kathryn Williams's turn - though she could use some tips from her predecessors when it comes to stage presentation. Sensitivity might be part of a singer-songwriter's job description but coming over all girlishly bashful in front of an audience is tiresome. Williams's low, dreamy tones and dolorously introspective material, interwoven with graceful cello accompaniment, initially cast a beguiling spell, but soon the unremitting languor of her sound became more soporific than soul-stirring.

It's becoming almost a tradition for the Cambridge Folk Festival line-up to include the female folky type who now seems to be an annual fixture on the Mercury Prize short list, announced just before the event got away at the weekend. With two previous holders of the office, Eliza Carthy and Kate Rusby, also in attendance, this year it was Kathryn Williams's turn - though she could use some tips from her predecessors when it comes to stage presentation. Sensitivity might be part of a singer-songwriter's job description but coming over all girlishly bashful in front of an audience is tiresome. Williams's low, dreamy tones and dolorously introspective material, interwoven with graceful cello accompaniment, initially cast a beguiling spell, but soon the unremitting languor of her sound became more soporific than soul-stirring.

If not quite a monstrous regiment, there was certainly a sizeable phalanx of female voices to be heard during Cambridge's 36th consecutive outing, as the microclimate engendered by the event's concentration on mellowed-out bonhomie defied a distinctly dubious weather forecast to create the traditional mass-picnic ambience. The high priestess of the folk revival, Joan Baez, led the chorus before a raptly appreciative Saturday night congregation, her pure, earnest soprano still ringing out true and clear, but her precise, almost formal enunciation of songs old and new sounding oddly dated alongside younger traditional torch-bearers such as Rusby and Carthy.

Though very different in style and timbre, both of England's favourite folk chicks possess an instinctive, expansive feel for the pulse and flow of a song, letting their voices inhabit the material where Baez seems to impose herself on it. Appearing at a superb afternoon session hosted by the young Scottish fiddle star John McCusker, Rusby commanded pin-drop silence for her nakedly heartrending delivery of a tragic love ballad, while a highlight of Carthy's set was an old English folk ditty spliced with a Caribbean courting song, a swinging, sun-dappled combination that brought out all the lustrous richness of Carthy's voice.

America's favourite folk chick, Ani DiFranco, has been rather dauntingly described as embodying "the soul of a shaman, the courage of an activist and the voice of a generation". It's a little difficult to get past the "righteous" bit of the self-styled Righteous Babe (it's what she calls her record label), especially in ballsy rock-out mode as she was on Friday night, imparting her words of wisdom to a vociferous throng of her own devoted faithful at the head of a full band line-up. She certainly doesn't want for charisma, possesses "attitood" aplenty and boasts a mighty pair of lungs, but she ended up sounding for all the world like a semi-plugged Alanis Morrisett.

Paul Heaton and Dave Rotheray, the songwriting duo behind The Beautiful South, were this year's booking for the artist-you-wouldn't-expect-to-find-at-a-folk-festival slot. Their warmly received set found them sounding more reminiscent of Heaton's Housemartins era than their current band incarnation, but a bitter-sweet rendition of "Don't Marry Her" kept the pop fans happy.

On the instrumental front, despite the heavyweight presence of Irish traditional legends De Dannan, and the renowned young Irish-American outfit Solas, the show was effectively stolen by the Basque accordionist Kepa Junkera. He comprehensively captivated a largely unsuspecting audience with a display of astonishing virtuosity, all butterfly-like ornamentation and prodigious dynamic range, he and his five-piece band simultaneously whipping up a frenzy of on-the-spot jigging with some of the most irresistible dance rhythms to be heard all weekend.