It can be terribly hard to convince people of the Indigo Girls’ worth. An air of plaid-shirted worthiness haunts them and, despite regularly clocking up gold albums in the US, they’ve never been more than a minor cult here. But listen, especially, to 1994’s gorgeous Swamp Ophelia (with guest harmonies from the divine Jane Siberry), the album that finds their immaculate songcraft at its most emotive, and you’ll see them as so much more than lumpy old bleeding-heart lesbians in big boots. All That We Let In, produced with stultifying politeness by longtime collaborator Peter Collins, is not going to change their fortunes in the UK, sadly. Emily Saliers and Amy Ray’s voices still combine to luscious effect, but the combination of tinkling pianos, gutsy strum and homespun wisdom places this very much in the middle of the road. What they really need to let in is air.