ing ▁characters ▁into ▁her ▁scripts . ▁By ▁May ▁ 1 9 8 2 ▁there ▁were ▁problems ▁with ▁a ▁script ▁by ▁Pat ▁M ills , ▁Song ▁of ▁the ▁Space ▁Wh ale , ▁which ▁had ▁been ▁intended ▁to ▁open ▁the ▁Black ▁Guardian ▁tr il ogy . ▁M ills ' ▁script ▁was ▁eventually ▁dropped ▁and ▁the ▁production ▁team ▁considered ▁moving ▁The ▁En light en ers ▁forward ▁in ▁the ▁season ▁to ▁replace ▁it , ▁necess it ating ▁considerable ▁re - w ites . ▁Peter ▁Gr im w ade ▁was ▁eventually ▁commission ed ▁to ▁write ▁M aw d ry n ▁Und ead ▁to ▁replace ▁The ▁Song ▁of ▁the ▁Space ▁Wh ale , ▁and ▁The ▁En light en ers ▁was ▁confirmed ▁as ▁the ▁fifth ▁serial ▁of ▁the ▁season . ▁▁ ▁The ▁first ▁draft ▁of ▁Part ▁One ▁did ▁not ▁contain ▁any ▁of ▁the ▁material ▁concerning ▁the ▁Guard ians , ▁and ▁T url ough ▁was ▁a ▁peri pher al ▁figure , ▁with ▁the ▁script ▁foc uss ing ▁on ▁the ▁relationship ▁between ▁Mar r iner ▁and ▁T eg an . ▁With ▁pre - production ▁under way , ▁Sa ward ▁changed ▁the ▁story ▁title ▁to ▁En light en ment ▁in ▁September ▁ 1 9 8 2 , ▁a ▁title ▁he ▁felt ▁was ▁more ▁en ig m atic . ▁Sa ward ▁also ▁re w rote ▁port ions ▁of ▁the ▁script ▁per tain ing ▁to ▁the ▁story - arc , ▁particularly ▁the ▁final ▁confront ation ▁scenes ▁at ▁the ▁end ▁of ▁Part ▁Four . ▁Peter ▁M off att ▁had ▁been ▁originally ▁scheduled ▁as ▁the ▁serial '