There are generally two ways of presenting folk music: to electrify/modernize it or to strive to present it as it was likely performed decades or centuries ago, with no variation or contemporary influences. Traditional British folk singer Kate Rusby opts for a rather nifty middle ground. She reaches into the rich history of the U.K. (not just England’s) folk tradition, albeit with judicious use of piano, drums and brass as seasoning, along with the usual guitar, whistle and accordion, but she doesn’t rock it up nor does she dumb it down in the quest for that Wider Audience. Rusby sings in a lilting, wistful, sweet-sad voice that’s downright captivating in its gentle, resigned sincerity, and she forgoes the stiff, staid “purity” that leads so many traditional performers to Dullsville. 10 is a retrospective of live, re-recorded and new songs spanning Rusby’s 10-year career that stacks up very well against her three solo albums (Rusby was also a member of The Poozies). And it serves as a definitive introduction to the sumptuous talents of Ms. Rusby.