Complex sentence: The name Leftfield was originally used simply by Barnes for his first single with editing/arranging and additional production added by Daley but, after this, Daley was involved in remixing "Not Forgotten" and then in the creation of all of Leftfield's works.
Split into simpler sentences: The name Leftfield was originally used by Barnes for his first single, with editing/arranging and additional production added by Daley. However, after this, Daley was involved in remixing "Not Forgotten" and then in the creation of all of Leftfield's works.