Miranda (1948)
Miranda is a 1948 British comedy film, directed by Ken Annakin and written by Peter Blackmore, who also wrote the play of the same name from which the film was adapted. Denis Waldock provided additional dialogue. A light comedy, the film is about a beautiful and playful mermaid played by Glynis Johns and her effect on Griffith Jones. Googie Withers and Margaret Rutherford are also featured in the film.
More at Wikipedia.