▁Conserv atives ▁and ▁the ▁Liber als ▁each ▁saw ▁their ▁vote ▁share ▁decl ine , ▁and ▁Conserv ative ▁Party ▁leader ▁Edward ▁He ath , ▁who ▁had ▁lost ▁three ▁of ▁the ▁four ▁elections ▁he ▁cont ested , ▁was ▁ou sted ▁as ▁party ▁leader ▁in ▁February ▁ 1 9 7 5 ▁and ▁replaced ▁with ▁future ▁Prime ▁Minister ▁Margaret ▁Th atch er . ▁The ▁Scottish ▁National ▁Party ▁won ▁ 3 0 % ▁of ▁the ▁Scottish ▁popular ▁vote ▁and ▁ 1 1 ▁of ▁Scotland ' s ▁ 7 1 ▁seats ; ▁it ▁was ▁their ▁most ▁successful ▁general ▁election ▁result ▁until ▁ 2 0 1 5 , ▁where ▁they ▁won ▁ 5 6 ▁of ▁ 5 9 ▁Scottish ▁seats ▁and ▁replaced ▁the ▁Liberal ▁Democr ats ▁as ▁the ▁third ▁largest ▁party ▁in ▁West min ster . ▁ ▁Sub sequently , ▁Labour ' s ▁narrow ▁parliament ary ▁majority ▁had ▁disappeared ▁by ▁ 1 9 7 7 ▁through ▁a ▁series ▁of ▁by - e lection ▁losses ▁and ▁defe ctions . ▁It ▁then ▁required ▁de als ▁with ▁the ▁Liber als , ▁the ▁Ul ster ▁Union ists , ▁the ▁Scottish ▁National ists ▁and ▁the ▁Wel sh ▁National ists . ▁ ▁This ▁was ▁the ▁last ▁general ▁election ▁victory ▁for ▁the ▁Labour ▁Party ▁until ▁ 1 9 9 7 ; ▁each ▁of ▁the ▁next ▁four ▁consecutive ▁general ▁elections ▁produced ▁a ▁Conserv ative ▁parliament ary ▁majority . ▁ ▁The ▁election ▁was ▁broadcast ▁live ▁on ▁the ▁BBC , ▁and ▁was ▁presented ▁by ▁David ▁Butler , ▁Al ast air ▁Burn et , ▁Robert ▁McK en zie , ▁Robin ▁Day