They don't write books like this any more and thank goodness they don't. Okay, it's of its time - 1954 - but the children (teenagers??) are rather priggish as well as snobs. Its 156 pages could well have been halved, if not more. Conversations that occupy a couple of pages could have been just as effective with a single question and answer. The plot is really dragged out and then the end (solution of the mystery) is over in a couple of sentences. And the denouement takes place with two men exchanging gunfire until one (the goodie) runs out of bullets at which point a third man (also a goodie) kills the baddie by throwing a knife at him. Very wholesome fare for children! I read this as a nostalgic exercise because I remember Monica Marsden as a children's broadcaster back when I was a little tacker (some 70 years ago!!). I really needn't have bothered.
This entire review has been hidden because of spoilers.