▁B ax ter ▁in ▁Secret ▁Di ary ▁of ▁a ▁Call ▁Girl , ▁an ▁I TV 2 ▁adaptation ▁of ▁Bro oke ▁Magn anti ' s ▁The ▁Int imate ▁Advent ures ▁of ▁a ▁London ▁Call ▁Girl , ▁a ▁mem oir ▁detail ing ▁the ▁life ▁of ▁a ▁high - class ▁prost itute ▁who ▁adopted ▁" B elle ▁de ▁J our " ▁as ▁her ▁pseud onym , ▁which ▁a ired ▁from ▁September ▁ 2 0 0 7 . ▁As ▁part ▁of ▁her ▁prepar ation ▁for ▁the ▁role , ▁Pi per ▁met ▁the ▁mem oir ' s ▁author ▁two ▁years ▁before ▁her ▁identity ▁as ▁a ▁research ▁scient ist ▁was ▁revealed ▁in ▁a ▁Sunday ▁newspaper : ▁" I ▁absolutely ▁had ▁to ▁meet ▁the ▁person ▁behind ▁the ▁words ▁to ▁be ▁able ▁to ▁take ▁the ▁part ... ▁people ▁did ▁ask ▁me ▁about ▁her ▁and ▁I ▁just ▁had ▁to ▁smile , ▁to ▁avoid ▁giving ▁anything ▁away ." ▁ ▁A ▁second ▁series , ▁with ▁Pi per ▁again ▁in ▁the ▁st arring ▁role , ▁started ▁film ing ▁in ▁May ▁ 2 0 0 8 , ▁during ▁which ▁two ▁body ▁doubles ▁were ▁h ired ▁to ▁hide ▁Pi per ' s ▁pre gn ancy ▁during ▁the ▁sex ▁scenes .. ▁Pi per ▁was ▁also ▁quoted ▁during ▁this ▁time ▁as ▁worry ing ▁that ▁she ▁may ▁have ▁" ru ined ▁her ▁future ▁career " ▁due ▁to ▁the ▁nature ▁of ▁the ▁to pl ess ▁scenes ▁and ▁other ▁sexual ▁scenes ▁required . ▁The ▁third ▁series ▁began ▁air ing ▁in ▁January ▁ 2 0 1 0 . ▁For ▁the ▁third ▁and ▁fourth