Doctor in the House S05E12 - There's No Fire Without Smoke

Duncan and Dick carry on playing cards during a fire drill, aware there is no fire but Sir Geoffrey is annoyed with their apathy and appoints them fire wardens. Urged by Sir Geoffrey to make the next fire drill as realistic as possible, Bingham causes a real fire but the brigade don't respond as they are used to hoaxes. Duncan and Dick panic and steal a fire engine only to discover that Sir Geoffrey has extinguished the flames himself. When the firemen eventually turn up they are not pleased with the doctors.