The Staves are a band composed of three sisters form Watford. Jessica is the one who plays guitar, Camilla plays the Ukelele (don't panic, it's not George Formby) and Emily gets to do the occasional keyboard or drum.
A review in the Guardian described them as like Angels forced to make their way in the music business.
The songs are all credited to the Staves, so it is not possible to disentangle who wrote what or how the writing partnership works.
It is difficult to describe who they sound like - I would suggest they are like singer-song writers form 70's California (in a good way) - Crosby Stills and Nash ? Peter Paul and Mary ? but with the voices of three women.
The harmonies are Divine - who knows they could go on to be massive stars, have a cult following or just fade away. I suspect they haven't yet written a chart hit - but who cares ?
and perhaps the best way to find out is to listen.