Flash Harry (George Cole (actor)) has set up a marriage bureau for the sixth form St. Trinian's girls and is in Rome negotiating with Prince Bruno (Guido Lorraine), who is interested in marrying one of them. The Prince suggests that Harry bring the girls to Rome before July, at the Prince's expense, so he can make a decision. Coincidentally, UNESCO is offering the best academically qualified school in England an expenses paid bus tour to various European cities, ending in Rome: they will play at the Vienna Music Festival and play in a series of field hockey and water polo matches against school teams. Of course, St Trinian's is the last possible candidate for the tour. Harry returns with the news of the Prince's offer, but is at a loss how to get the girls to Rome before their term ends in July. The UNESCO tour provides the solution, when the girls, led by sixth form girls Bridget Strong (Dilys Laye), Cynthia (Jose Read), and Annabel (Rosalind Knight), break into the Ministry of Education in London and replace their file with one reporting their outstanding academic qualifications, assuring they will be chosen.