If it gets to the point when you are climbing up cliffs and you have to say to your companion, as one of the boys in this film does, "I don't think I can quite make it", either up or down, that is when you will be hugely grateful to members of the RAF Valley Search & Rescue service who are always ready to look for and save the reckless, the unlucky and the injured. You may spare a thought, too, for the good citizens who know that such a service can be contacted by telephone in an emergency.