▁film ing ▁dates , ▁being ▁committed ▁to ▁film ing ▁Last ▁of ▁the ▁Summer ▁W ine ▁and ▁was ▁forced ▁to ▁drop ▁out ▁of ▁the ▁production , ▁being ▁replaced ▁by ▁Keith ▁Bar ron . ▁ ▁Ly nd a ▁Baron ▁was ▁cast ▁as ▁Captain ▁W rack , ▁having ▁previously ▁participated ▁in ▁Doctor ▁Who ▁in ▁the ▁ 1 9 6 6 ▁serial ▁The ▁Gun fig h ters , ▁as ▁the ▁voice ▁that ▁s ings ▁the ▁" B all ad ▁of ▁the ▁Last ▁Ch ance ▁Sal oon " ▁heard ▁throughout ▁that ▁story . ▁Tony ▁Ca unter , ▁who ▁had ▁previously ▁played ▁Th atch er ▁in ▁The ▁Cr us ade ▁and ▁Morgan ▁in ▁Col ony ▁in ▁Space ▁was ▁given ▁the ▁role ▁of ▁Jackson , ▁with ▁Christopher ▁Brown ▁and ▁David ▁Rh ule ▁being ▁cast ▁as ▁Mar r iner ▁and ▁W rack ' s ▁side k ick ▁Mans ell ▁respectively . ▁Similarly ▁to ▁S all is , ▁David ▁Rh ule ▁was ▁un available ▁for ▁the ▁re vised ▁film ing ▁dates ▁in ▁January , ▁so ▁singer ▁Le ee ▁John ▁replaced ▁him ▁at ▁short ▁notice , ▁despite ▁having ▁no ▁previous ▁acting ▁experience . ▁ ▁Valent ine ▁Dy all ▁had ▁originally ▁played ▁the ▁Black ▁Guardian ▁in ▁the ▁ 1 9 7 9 ▁serial ▁The ▁Arm aged don ▁F actor , ▁the ▁character ' s ▁first ▁appearance ▁in ▁the ▁series , ▁and ▁repr ised ▁the ▁role ▁for ▁season ▁ 2 0 , ▁appearing ▁in ▁M aw d ry n ▁Und ead , ▁Term inus ▁and ▁En light en ment . ▁Similarly ▁Cy ril ▁L uck