The 'solo' project of Isobel Campbell (formerly of Belle and Sebastian, from which it borrows many members). They now have two albums out, The Green Fields of Foreverland and Swansong for You. The first is full of sweet, folksy lullabies and fairytale ballads, with a couple of incongruously rollicking danceable numbers thrown into the mix.
The second album is more mature, perhaps, and far more richly instrumented, showing influences from the heyday of swing-beat and jazz as well as the world of folk. Bel's voice is honey-sweet and breathy, small but powerful; her songs are for the most part mournful but full of hope.
Isobel has said that she won't be releasing any more albums as The Gentle Waves. Her next record, an album of Billie Holliday covers, will be released under her own name.