Versatile stage and screen actor who found TV comedy fame as Sybil Fawlty and later played Elizabeth II on stageAlthough it became virtually a weekly occurrence to find Queen Elizabeth II treading the boards in recent years, the first time a reigning monarch was portrayed on the contemporary British stage came when Prunella Scales, who has died aged 93, played Her Majesty in Alan Bennett’s A Question of Attribution at the National Theatre in 1988.She did so to the displeasure of the NT&rsq