▁Sw ind on ▁seat ▁in ▁a ▁by - e lection , ▁but ▁lost ▁it ▁a ▁second ▁time ▁at ▁the ▁ 1 9 3 5 ▁general ▁election . ▁During ▁the ▁Spanish ▁Civil ▁War ▁he ▁helped ▁organ ise ▁medical ▁aid ▁to ▁Spain . ▁▁ 1 9 3 7 – 1 9 5 1 ▁In ▁May ▁ 1 9 3 7 , ▁Add ison ▁joined ▁the ▁Labour ▁party ' s ▁me ag re ▁c au cus ▁in ▁the ▁House ▁of ▁L ords , ▁being ▁raised ▁to ▁the ▁peer age ▁as ▁Baron ▁Add ison , ▁of ▁St alling borough ▁in ▁the ▁County ▁of ▁Lincoln . ▁He ▁was ▁Chair man ▁of ▁the ▁Buck ingham shire ▁War ▁Agricult ural ▁Committee ▁during ▁the ▁Second ▁World ▁War , ▁co - ordin ating ▁agricult ural ▁production ▁and ▁supply ▁in ▁that ▁county . ▁Att lee ▁appointed ▁Add ison ▁to ▁be ▁Labour ' s ▁leader ▁in ▁the ▁L ords ▁in ▁ 1 9 4 0 , ▁after ▁Lord ▁S nell ▁stepped ▁down ▁for ▁health ▁reasons . ▁Add ison ▁retained ▁this ▁position ▁until ▁his ▁death , ▁serving ▁as ▁Le ader ▁of ▁the ▁House ▁of ▁L ords ▁following ▁Labour ' s ▁victory ▁in ▁the ▁ 1 9 4 5 ▁general ▁election . ▁He ▁was ▁created ▁Vis count ▁Add ison , ▁of ▁St alling borough ▁in ▁the ▁County ▁of ▁Lincoln , ▁in ▁July ▁ 1 9 4 5 . ▁ ▁As ▁Le ader ▁of ▁the ▁House ▁of ▁L ords , ▁Add ison ▁had ▁the ▁key ▁responsibility ▁of ▁ste ering ▁government ▁legisl ation ▁through ▁the ▁upper ▁chamber .