In an era where virality defines success, Joe and Dave Dunwell stand apart. The Leeds lads’ family band busked in railway stations as recently as last April, but has been hard at work for more than a decade (the boys made a U.S. national TV debut with a 2012 appearance on Jay Leno’s “Tonight Show”). In the midst of a mission to become a great British band, The Dunwells bring a tried and true brand of harmonious folk-rock to this intimate Clearwater gig.—Ray Roa