RA ▁terror ism . ▁However , ▁in ▁a ▁document ary , ▁The ▁Plot ▁Again st ▁Harold ▁Wilson ▁in ▁ 2 0 0 6 , ▁Baron ess ▁F alk ender ▁assert ed ▁that ▁the ▁government ▁was ▁not ▁informed ▁in ▁advance . ▁The ▁occupation ▁of ▁He ath row ▁was ▁priv ately ▁seen ▁at ▁Number ▁ 1 0 ▁as ▁a ▁warning ▁to ▁Wilson ▁by ▁the ▁Army , ▁or ▁even ▁a ▁dress ▁re he ars al ▁for ▁a ▁coup ▁d ' et at . ▁▁ 1 9 ▁July ▁ 1 9 7 5 : ▁London ▁Under ground ' s ▁ ▁Pic c ad illy ▁line ▁extension ▁from ▁H oun slow ▁West ▁opened ▁as ▁far ▁as ▁Hat ton ▁Cross . ▁▁ 1 9 7 7 : ▁The ▁Pic c ad illy ▁line ▁opened ▁from ▁Hat ton ▁Cross ▁to ▁He ath row ▁Central , ▁putting ▁the ▁air port ▁within ▁just ▁under ▁an ▁hour ' s ▁journey ▁of ▁Central ▁London . ▁▁ 1 9 8 0 s ▁ ▁Early ▁ 1 9 8 0 s : ▁By ▁now , ▁annual ▁passenger ▁numbers ▁had ▁increased ▁to ▁ 3 0   mill ion , ▁and ▁required ▁more ▁terminal ▁space . ▁As ▁a ▁result , ▁Terminal ▁ 4 ▁was ▁constructed ▁to ▁the ▁south ▁of ▁the ▁southern ▁run way , ▁on ▁the ▁site ▁of ▁farm ▁or ▁far ms ▁called ▁May fields ▁and ▁May field ▁Farm , ▁next ▁to ▁the ▁existing ▁cargo ▁terminal ▁and ▁away ▁from ▁the ▁three ▁older ▁terminal s ▁with ▁connections ▁to ▁Term inals ▁ 1 , ▁ 2 ▁and ▁ 3 ▁provided