Over the next few years, Spawton and Poole retreated to their studio, slowly writing and recording the material that would become 2002's Bard. The lineup continued to shift, with the core duo remaining the band's creative center. Their next release, a 2004 conceptual album called Gathering Speed, was dedicated to the airmen and women who perished in the Battle of Britain. It was seen as a return to more traditional prog rock and was the first to feature new vocalist Sean Filkins. 2007's The Difference Machine was a similarly detailed, deeply progressive album that hosted several guest musicians who would eventually join the band full-time. At this point in their career, Big Big Train had established themselves as a veteran and respected presence among other second- and third-wave prog bands like Marillion and Spock's Beard, the latter of whom provided their next drummer, Nick D'Virgilio. With a new vocalist in David Longdon, they recorded their sixth album, The Underfall Yard (2009), an exploratory work that played nostalgically on historical themes and featured guest spots from former XTC guitarist Dave Gregory, among others. A long EP called Far Skies Deep Time arrived the following year and featured Gregory, as well as members of French pop auteur Louis Phillipe's band. With a 17-minute epic saga about Belgian pop star Jacques Brel's last voyage, it played up Big Big Train's distinctive melding of thoughtful British pop and classical, progressive themes.
The year 2011 saw a deluxe remix and remaster of the band's debut, Goodbye to the Age of Steam. Their seventh and eighth albums would roll out as a two-part set called English Electric, Pt. 1 (2012) and Pt. 2 (2013). The two albums garnered critical acclaim, ironically earning the veteran band the Breakthrough Act award at the 2013 Progressive Music Awards. By this point, Big Big Train had been operating as a studio project for well over a decade, but 2015 would see not only a new EP (Wassail), but their first live performance in 17 years. With a lineup that included Dave Gregory (now a full-time member), new violinist Rachel Hall, Beardfish frontman Rikard Sjöblom, and a five-piece brass ensemble, Big Big Train sold out a three-night stand at King's Place in London in August 2015. Their ninth studio album, Folklore, arrived in May of 2016. Later that winter, Big Big Train began work on a new EP, but soon found that they had enough material for a proper full-length. The resulting Grimspound, which featured a guest appearance from former Fairport Convention singer Judy Dyble, arrived in April 2017. Latter-day vocalist David Longdon died on November 20, 2021 at the age of 56. ~ Timothy Monger, Rovi