Short: UK Electronical Composer, Musician and Producer, by the name of Nicholas Bracegirdle. Disco Citizens is an alias used by Nicholas Bracegirdle before he started using his more famous pseudonym Chicane.
He used it for three singles, Right Here Right Now (1995), Footprint (1997) and Nagasaki Badger (1998). He also remixed several tracks under the Disco Citizens guise.

Read more about Disco Citizens on Last.fm.