Four Jacks was a Danish vocal quartet, founded in 1956 by Poul Rudi and Otto Brandenburg.
John Mogensen joined shortly afterwards, and gradually took over the creative leadership.
Brandenburg left in 1958 to pursue a successful solo career [1] and was replaced by James Rasmussen.
In 2005, a re-release of the group's hits reached number one in the Danish Top 40 charts.
[3] In the English-speaking world, the group is perhaps best known for their version of Oley Speaks' On the Road to Mandalay.