This, the 55th Cambridge Folk Festival, is the one that dared to be different. Cambridge Folk Festival is the biggest festival of acoustic music in the world. In half a century, it has come a long way from simple folk. This year was the first time there was ballet on the main stage. It's true, you've never really heard a piece of music until you have seen people dance to it. The Sisters of Elva Hill is presented by The Henwives Tales, set up by folk singer Lucy Ward and choreographer Deborah Norris. The ballet bring together traditional folk musicians and classical dancers. Accompanied by a fiddle, Lucy Ward sings a tale of a spell cast on a princess and a lively ballet based on the story entrances the audience. Having wowed the main stage audience on Friday afternoon. The ballet was repeated in the early evening in the festival's wild flower garden. Young dancers from Cambridge's Netherhall School joined the professionals. The four-piece RURA are a powerhouse of modern Scottish music, though they play traditional Celtic instruments, including the bagpipes, they have an irresistable rock and roll energy. In complete contrast (to anything you have ever seen really) later in the afternoon the main stage offered Ben Caplan. In another life, he would have been a rabbi - or a singer in a synagogue (in the centuries before microphones they needed to have rich baritone voices). He has the beard for it. His publicity says this Canadian singer-songwriter has the sort of voice that can pour oil on troubled waters - before applying a match to it. He is passionate about the plight of refugees. He wants us to see the struggling and destitute human being who we label as migrant. This was a bit of a theme at this year's festival, Caplan's current touring set is based on a musical play called Old Stock: A Refugee Love Story, which began at the Edinburgh Fringe. But Caplin's music is not maudlin. It's loud and it makes you want to move. With piano, accordion, organ, saxophone, violin, drums, banjo, guitar - and a wonderful kletzma clarinet. He had the audience rocking. On a smaller stage, over in the Club Tent, also energising and uplifting were Max Bianco and the Bluehearts. This six-piece really know how to cook up pizzazz, with acordion, guitars, fiddle, accoustic bass and cajun. Bianco is a showman. The audience loved them. "See you next year on the main stage," he said. I would not be surprised. But there were moving, quieter moments too. In the intimate space of the Club Tent, on a sunny afternoon, The Clare Hayes Trio sang a moving song about the Falklands War. It could have been any war. This was followed by Woodie Guthrie's Poor Wayfaring Stranger. With voice, guitar and violin, theirs was a gently pleasing set leaving you wanting more. It was fast and furious again, in Stage 2 to end the evening. The Tweed Project, with songs sung in Scots Gaelic, unites English and Scottish traditions. It has four BBC Radio 2 Folk Award winners, Greg Russell (vocals, guitar and bouzouki) Ciaran Algar (fiddle) Celtic singer Josie Duncan and guitarist Pablo Lafuente. Plus flautist Ali Levack and Evan Carson on drums. Supreme musicianship here in the festival's time-honoured, Celtic tradition and a privilege to hear. The boundaries were stretched again by Tunng, This London six-piece are leading lights in "folktronica" blending acoustic music with synthesizers and samples. The result is, as it were, electric. The audience loved it. There was a real atmosphere of energy and warmth by the time they had finished playing. And the evening in Stage 2 finished with a roar. Holy Moly and the Crackers are well-named. Possibly with roots in folk and blues, but now firmly gone over to rock and roll and garage punk. It's loud and it had the tent leaping up and down. Led by singer and fiddle player, Ruth Patterson with Conrad Bird on vocals, guitar and trumpet, it also has Rosie Bristow accordion, Nick Tyler electric guitar, Jamie Shields bass and Tommy Evans drums and backing vocals. They closed the night with verve.