Trees were here and gone, quickly – across four years, 1969 to 1972 – but in that time, they recorded two gorgeous folk-rock albums that summed up most of what was so great about the genre. The ensemble playing on their second album, On The Shore, is what makes it, along with Celia Humphris’s crystal-clear voice. The version of Cyril Tawney’s “Sally Free and Easy” here is perhaps the definitive rendering of that song, full of drama and unexpected turns – the rumbling, improvised piano at its beginning makes way for a group sound that’s intoxicating, the guitars of Barry Clarke and David Costa looping and curling around each other, with a fluidity only really matched, in British folk rock, by the likes of Richard Thompson and Martin Carthy. That strangely eerie cover, by Hipgnosis, only adds to the mystique.