Up Pompeii (1971)

A funny thing happens to Lurcio (Frankie Howerd) on the way to the rent-a-vestal-virgin market stall. A mysterious scroll falls into his hands, listing the names of all the conspirators plotting to murder Emperor Nero. And when the upstart slave is elected to infiltrate the ringleader's den, the comical ups-and-downs lead to total uproar.