▁from ▁Ken ning ton ▁to ▁B atter se a ▁is ▁currently ▁under ▁construction , ▁which ▁may ▁either ▁give ▁the ▁Northern ▁line ▁a ▁second ▁southern ▁branch ▁or ▁may ▁see ▁it ▁split ▁into ▁separate ▁distinct ▁lines ▁with ▁their ▁own ▁ident ities . ▁It ▁is ▁col oured ▁black ▁on ▁the ▁current ▁T ube ▁map . ▁ ▁History ▁ ▁Form ation ▁See ▁City ▁and ▁South ▁London ▁Railway ▁and ▁Char ing ▁Cross , ▁E ust on ▁and ▁H amp st ead ▁Railway ▁for ▁detailed ▁histor ies ▁of ▁these ▁companies ▁ ▁The ▁core ▁of ▁the ▁Northern ▁line ▁evol ved ▁from ▁two ▁railway ▁companies : ▁the ▁City ▁& ▁South ▁London ▁Railway ▁( C & SL R ) ▁and ▁the ▁Char ing ▁Cross , ▁E ust on ▁& ▁H amp st ead ▁Railway ▁( CCE & HR ). ▁ ▁The ▁C & SL R , ▁London ' s ▁first ▁deep - level ▁t ube ▁railway , ▁was ▁built ▁under ▁the ▁super vision ▁of ▁James ▁Henry ▁Great head , ▁who ▁had ▁been ▁responsible , ▁with ▁Peter ▁W . ▁Bar low , ▁for ▁the ▁Tower ▁Sub way . ▁It ▁was ▁the ▁first ▁of ▁the ▁Under ground ' s ▁lines ▁to ▁be ▁constructed ▁by ▁b oring ▁deep ▁below ▁the ▁surface ▁and ▁the ▁first ▁to ▁be ▁operated ▁by ▁electric ▁tra ction . ▁The ▁railway ▁opened ▁in ▁November ▁ 1 8 9 0 ▁from ▁Stock well ▁to ▁a ▁now - dis used ▁station ▁at ▁King ▁William ▁Street . ▁This ▁was ▁incon ven ient ly ▁placed ▁and ▁unable ▁to ▁co pe ▁with ▁the ▁company ' s ▁traffic