A nice part for Rita, probably one of her biggest in films.She plays "Cassandra the soothsayer", popping up throuhout the film. 
The first scene is near the begining, standing at the top of the stone steps she shouts " Wow, wow and thrice wow" Frankie Howerd turns to camera and quips "Oh dear. This is Cassandra, the soothsayer" and looks back at her. Rita rants "Oh wicked people of Pompei repent your evil ways, for I have been high on 'Vesubio' and the Gods have given me a sign!" The crowd laugh as Frankie adds "Oh know, don't laugh. It's wicked to mock the aflicted" 
Rita starts again "Repent now I say or suffer the evil fate that befell the wicked people of Gamorra" Frankie mocks "Quite, quite" as Rita in front of Frankie exclaims "And soddom!" Frankie quips back "I quite agree dear, the lot of 'em" 
Rita stretches out her arms and shouts "Skys will grow dark. The wind will howl. Fire and brimestone will rain down upon the city, and all will famish in the flames." she starts walking through the crowd and out of shot crying "Oh wow, wow" 
The camera turns back on Frankie who says "Oh she is a misery isn't she! Still I feel sorry for her, poor soul. Because she's very inbittered you know, oh very inbittered. Did you notice that ring she had on?, well apparently that was given to her by the man she loved when she was 18. well he left her, and she's never had it off since! Oh it is a shame."

The next time we see Rita is when Frankie is in a tight spot with some guards.As he is pinned against the wall at sword point Rita enters exclaiming "Repent of your evil ways sinners of Pompei, or Pompei will be destroyed. More warnings will follow. I Cassandra for see it!" 
Frankie has given the guards the slip and runs away to hide. Rita keeps reappering as explosions are heard, she shouts "Oh great jupiter show them I speak the truth" the scene cuts back to Frankie and then back to Rita shouting "Send them a sign" at this moment two large clay pots of boiling water explode where Frankie is hiding, Rita excitedly quips "The gods are working well tonight"

When frankie has to fight "Gargo" the wrestler (played by Bernard Bresslaw) Rita is seen in the crowd jeering Frankie on. Eventually he gets thrown into the crowd and onto Rita's lap, she tells him "You will come to no harm, the gods have spoken" he replies "Well they may have spoken to you, but have they spoken to Gargo!"

Rita is seen again when Frankie is running amock in the palace, Rita comes towards him crying "The prophecy of the gods will be forfilled" Frankie runs past her as she asks him "Wait, don't you feel anything?" he replies "I rarely get the chance dear, and i've no time now" 
she grabs hold of him by his pants and says "The end is near, all will soon be revealed!" Frankie snaps at her "It will if you don't let go of my knickers! Do you mind" she carries on "Repent ye, before it is too late"

At the end of the film after Pompei is destroyed Rita appears amongst the ruined city shouting "Oh wow, wow and thrice wow. The end is near. Pompei is destroyed and it's disgusting inhabitants turned to stone" she looks down at Frankie and says "What's this one remaining?" he quips "Don't include me dear i'm off" she shouts back "Witherest thou away" he replies "yes and I can't blame the weather" Rita finally rants "You shall not escape the wrath of the gods. You too shall be a stone, oh Pompei utterly destroyed. Oh Pompei, Pompei is destroyed, oh wow (The last bit of dialogue is heard slowely fading away while Frankie faces camera and delivers his speech)

Rita is seen once more as Frankie in modern times takes a bunch of tourists on a tour of the stone statues in Pompei. Rita is dressed as a nun and after looking at a couple in bliss turned to stone, she rushes off with the familiar "Oh wow, wow and thrice wow, the gods have spoken" following her.