Last night (Feb. 23), while performing at Gloucester Guildhall, King Charles ushered a very special guest onto the stage. Mumford and Sons' lead man Marcus Mumford joined the singer-songwriter onstage to perform three songs, including "Loose Change." You can watch footage of all three songs in the video above.

Mumford's cameo, while appreciated, shouldn't come as ultra surprising; he's actually worked with King Charles in the past. He greeted the audience with a simple "Hello," sporting a black hat and rocking the electric guitar while singing with King Charles during each song.

Mumford and Sons have recently been announced as the headliners for not only Reading and Leeds, their first major European appearance since 2013, but also this year's Bonnaroo. (Metallica will join Mumford and Sons as co-headliners for Reading and Leeds, and a third headliner will be announced very soon.) Mumford and Sons are reportedly in the studio, working on a follow-up to 2012's Babel with Arctic Monkeys and Haim producer James Ford.

King Charles are currently on a 28-day tour in 28 days this February, about half of which has been sold out. His full itinerary can be found via here.