▁Broadcast ing ▁technology ▁▁ 4 0 5 ▁line ▁system ▁ ▁Television ▁broadcast ing ▁began ▁on ▁an ▁experimental ▁basis ▁by ▁the ▁BBC ▁in ▁London ▁in ▁ 1 9 3 6 ▁on ▁V H F ▁Band ▁I . ▁Initial ly ▁the ▁service ▁was ▁operated ▁using ▁two ▁compet ing ▁systems : ▁ ▁The ▁earliest ▁television ▁broadcast s ▁used ▁the ▁ 2 4 0 - line ▁B air d ▁system ▁and ▁the ▁ 4 0 5 - line ▁Mar con i - E MI ▁system ▁on ▁alternate ▁weeks . ▁However , ▁the ▁B air d ▁system ▁proved ▁too ▁cum bers ome ▁and ▁by ▁early ▁ 1 9 3 7 ▁had ▁been ▁dropped ▁and ▁the ▁Mar con i - E MI ▁system ▁became ▁the ▁standard . ▁This ▁system ▁was ▁later ▁cod ified ▁by ▁the ▁IT U ' s ▁CC IR ▁( now ▁IT U - R ) ▁on ▁an ▁international ▁conference ▁in ▁Stockholm ▁in ▁ 1 9 6 1 ▁as ▁System ▁A . ▁ ▁D ifferent ▁broadcast ▁stations ▁across ▁the ▁country ▁were ▁broadcast ▁on ▁different ▁channels ▁to ▁avoid ▁inter ference ▁and ▁allow ▁for ▁regional ▁variations . ▁ ▁Broadcast ▁was ▁susp ended ▁during ▁the ▁Second ▁World ▁War ▁but ▁res umed ▁in ▁ 1 9 4 6 . ▁The ▁BBC ▁was ▁joined ▁on ▁this ▁system ▁in ▁ 1 9 5 5 ▁with ▁the ▁launch ▁of ▁commercial ▁television ▁in ▁the ▁form ▁of ▁the ▁regional ▁Independent ▁Television ▁( IT V ) ▁network , ▁managed ▁by ▁the ▁Independent ▁Television ▁Author ity ▁( IT A ), ▁which ▁also ▁saw ▁the ▁use ▁of ▁V H