The standout acting performance is Robert Morley, playing Cliff's father who is also incidentally the property developer who wants to build an office block on the night club. Slightly more uneasy is Carole Gray as Cliff's romantic interest, partly because Cliff himself doesn't exude sufficient lust to match her. She went on to a brief but notable career in horror films. My whimsical reason for watching the film was the other main female character, Barbara, who is played by Annette Robinson who appeared four years later in Doctor Who as Anne Chaplette in The Massacre. Here she has long red hair, and isn't quite as confident as Carole Gray (there is one scene where she repeatedly declares that she is Cleopatra for some reason). Also noted: to a dyed blond Melvyn Hayes, playing one of Cliff's male sidekicks, and future sitcom star Richard O'Sullivan, playing the other one.
Anyway, one doesn't really watch this for the acting. The point of the film for Cliff to sing some slow romantic songs, including the title piece (which he sings to Gray walking through a park, surrounded by children who mob the couple as they are about to kiss), and he does it very well; and we don't quite get enough of The Shadows, but what we get is great. Even better, however, are the absolutely stunning dance scenes of Cliff's friends preparing and performing their show. I found this reminiscent of the great Gene Kelly sequences in Singin' in the Rain and An American in Paris, except that they are less focussed on the star (Cliff not being as notable a dancer as a singer) and also make a lot more sense in the context of the film. This is some of the best choreography I can remember seeing on screen, and it's reason enough on its own to hunt down the film.