is sent to the Ministry, advising them to let the girls partake on the UNESCO tour. With no choice, they decide to grant the request, and seeks volunteers to chaperone the girl and act as interpreters. Superintendent Kemp-Bird, who is berated for his failure to find Mangan – as he is wanted for a jewellery robbery in London – receives word from the Ministry about St. Trinian's plans. He decides to assign Sergeant Ruby Gates to go undercover as an interpreter, while advising the Ministry to secure coaches from a company belonging to Captain Romney Carlton-Ricketts, as its the only coach company that will transport the students mainly out of desperation. As the students prepare to depart, Mangan finds he must remain in disguise and accompany the girls on their tour. Because he still is in possession of the stolen jewels he took, he finds himself forced to hide them in a water polo ball, unaware that a sixth form student witnesses this. The girls soon cause chaos when visiting the cities on the tour, including Paris and Vienna. During this time, Romney makes a play for Gates due to her cover story, but as they reach Rome, she admits the truth to him, revealing that she has discovered Mangan amongst the students. When the girls prepare to play a water polo match before Bruno, chaos ensues when Mangan loses the ball containing the jewels, and is forced to steal it back. As he escapes with it, he is pursued by the fourth form students, who capture him at the Coliseum. As Prince Bruno announces his plans to marry Myrna, much to the annoyance of one of her sixth form classmates, St. Trinian's is given the reward for Mangan's capture, which Miss Fritton keeps for herself and the school upon her return. Meanwhile, Gates, now back in England, parts way with Romney to be with Kemp-Bird, who was demoted to the ranks after causing embarrassment for his superiors for attempting to arrest Hackshaw. Cast George Cole as "Flash Harry" Joyce Grenfell as Policewoman Sergeant Ruby Gates Terry-Thomas as Captain Romney Carlton-Ricketts Lloyd Lamble as Superintendent Kemp-Bird Terry Scott as Police Sergeant Lionel Jeffries as Joe Mangan Thorley Walters as Major Whitehart Cyril Chamberlain as Army Captain Judith Furse as Dame Maud Hackshaw Kenneth Griffith as Charlie Bull Alastair Sim as Miss Fritton Guido Lorraine as Prince Bruno Charles Lloyd Pack