▁years ▁in ▁the ▁army ▁during ▁World ▁War ▁II , ▁he ▁remained ▁in ▁the ▁profession . ▁ ▁Career ▁His ▁first ▁stage ▁appearance ▁was ▁at ▁the ▁Festival ▁Theatre , ▁Cambridge ▁in ▁ 1 9 3 7 , ▁and ▁he ▁went ▁on ▁to ▁appear ▁in ▁plays ▁at ▁both ▁the ▁West ▁End ▁in ▁London , ▁and ▁Broadway ▁in ▁New ▁York . ▁ ▁In ▁ 1 9 5 5 ▁he ▁appeared ▁on ▁stage ▁in ▁Wit ness ▁for ▁the ▁Pro sec ution ▁at ▁Henry ▁Miller ' s ▁Theatre ▁in ▁New ▁York ▁City , ▁and ▁on ▁film ▁as ▁Air ▁Vice - Mar shal ▁The ▁Hon ou rable ▁Ralph ▁C och rane ▁A FC ▁R AF , ▁A OC , ▁No . ▁ 5 ▁Group ▁R AF ▁in ▁The ▁Dam ▁B ust ers ▁( 1 9 5 5 ). ▁ ▁He ▁is ▁perhaps ▁best ▁remembered ▁for ▁his ▁role ▁as ▁the ▁ir as cible ▁Professor ▁Geoff rey ▁Lo ft us ▁in ▁the ▁television ▁comedy ▁series ▁Doctor ▁in ▁the ▁House ▁and ▁its ▁sequ els , ▁apart ▁from ▁Doctor ▁at ▁Sea , ▁in ▁which ▁he ▁appeared ▁as ▁Captain ▁Norman ▁Lo ft us ▁( the ▁brother ▁of ▁Professor ▁Lo ft us ). ▁He ▁also ▁appeared ▁as ▁the ▁Dean ▁in ▁the ▁BBC ▁sit com ▁All ▁Gas ▁and ▁G ait ers ▁( 1 9 6 7 – 7 1 ). ▁ ▁Clark ▁was ▁president ▁of ▁the ▁actors ' ▁trade ▁union ▁Equ ity ▁from ▁ 1 9 6 9 ▁to ▁ 1 9 7 3 . ▁ ▁Personal ▁life ▁He ▁married ▁three ▁times : ▁one ▁of ▁his ▁w