This is quite an enjoyable vehicle for a mischievous Glynis Johns, who doubles up as a gymnastics teacher ("Caroline") who is left a remote house on the Cornish coast, and a mermaid ("Miranda") who lives with her equally cheeky friend "Berengaria" (Dora Bryan) in a cave underneath. The two characters have a common ancestor and look identical, so when "Caroline" heads off on a cycling trip, her merver mais...