Alastair Sim portrays Wetherby Pond, a schoolmaster seeking tranquility with his unruly students at Nutbourne School. The backdrop is wartime, and bureaucratic officials in London decree that he must accommodate another institution on his grounds. However, the process becomes tangled in administrative procedures, leading to the arrival of the formidable Miss Whitchurch and her contingent of hundreds of girls, along with their belongings, hockey equipment, and more. Almost immediately, Pond and his staff find themselves outsmarted, and his shirts are relegated to storage. A tentative agreement arises when both sides recognize that their students possess stationery supplies—a prospect that fills them with dread as they contemplate writing letters to parents about the shared arrangement. Collaboration becomes essential. An unexpected inspection threatens the professional futures of everyone involved unless a clever scheme for resource sharing can be implemented swiftly. The film then devotes much of its remaining time to showcasing an impressive level of meticulousness that would have been remarkable even during the D-Day operations. Sim and Rutherford display exceptional comedic timing, while Frank Launder and John Dighton’s adaptation of Dighton's play provides them with plenty of chances to demonstrate it. A capable supporting cast, including Joyce Grenfell, contributes to the film's eighty minutes of lighthearted chaos and amusement.

Source on TMDB