Present Arms In Dub is a remix album by UB40 released in October 1981. The album contains eight remixed instrumental versions of original tracks from Present Arms and its bonus 12" single; only the double-A side single tracks "Don't Let It Pass You By"/"Don't Slow Down" are not included. The album was the first dub music album to hit the UK top 40. The dub style is characterized as a mainly instrumental version of an existing song, typically emphasizing the drums and bass.
The track listing shows that most of the dub versions have different song names to those used on Present Arms.
Although it would appear logical that "Return of Dr X" is the dub version of "Dr X", according to the CD versions of the two albums (and the samples on the band's official website), "Smoke It" is based on "Dr X"; "Return of Dr X" is based on "Don't Walk on the Grass". This is either intentional, or a labelling mistake made when the bonus 12" single tracks were added to the CD release of Present Arms.