The pair, Lindsey Troy and Julie Edwards, collaborated with the banjo player on the Italian leg of their European co-touring stint.
The song’s title is not known, but it’s expected to feature on the band’s upcoming debut album, due later this year.
Deap Vally are currently opening for Mumford on their entire European tour. Watch the clip below:
Check out our Best Fit session with Deap Vally here.