▁Hend erson ▁v ▁Arthur ▁[ 1 9 0 7 ] ▁ 1 ▁K B ▁ 1 0 ▁Business ▁Environment ▁Bow ▁Lane ▁Ltd ▁v ▁Dean water ▁Est ates ▁Ltd ▁[ 2 0 0 7 ] ▁E W CA ▁C iv ▁ 6 2 2 ▁ ▁Exception s ▁where ▁par ol ▁evidence ▁is ▁adm iss ible ▁G illes pie ▁B ros ▁& ▁Co ▁v ▁Chen ey , ▁E gg ar ▁& ▁Co ▁[ 1 9 8 6 ] ▁ 2 ▁Q B ▁ 5 9 , ▁to ▁prove ▁that ▁terms ▁need ▁to ▁be ▁imp lied ▁in ▁the ▁agreement ▁H utton ▁v ▁Warren ▁( 1 8 3 6 ) ▁ 1 ▁M & W ▁ 4 6 6 , ▁to ▁prove ▁custom ▁to ▁be ▁imp lied ▁in ▁the ▁agreement ▁Campbell ▁Dis count ▁Co ▁v ▁Gall ▁[ 1 9 6 1 ] ▁ 1 ▁Q B ▁ 4 3 1 , ▁to ▁show ▁the ▁contract ▁is ▁invalid ▁for ▁mis re presentation , ▁mistake , ▁fra ud ▁or ▁non ▁est ▁fact um ▁and ▁to ▁show ▁a ▁document ▁should ▁be ▁rect ified ▁P ym ▁v ▁Campbell ▁( 1 8 5 6 ) ▁ 6 E & B ▁ 3 7 0 , ▁to ▁show ▁a ▁contract ▁is ▁not ▁yet ▁oper ative , ▁or ▁has ▁ceased ▁Mann ▁v ▁N unn ▁( 1 8 7 4 ) ▁ 3 0 ▁L T ▁ 5 2 6 , ▁to ▁prove ▁a ▁coll ater al ▁agreement ▁exists ▁ ▁Notes ▁ ▁References ▁Andrew ▁Bur rows , ▁Case book ▁on ▁Cont ract ▁( H art