Though a lot less romantic than the Chuck Yeager section of The Right Stuff, this clipped British account of the breaking of the sound barrier is an entirely fictionalised version of events the later film records fairly accurately. Rather than a drama of individual heroism, this is a story of stalwart teamwork, with boffin Richardson fooling around in the laboratory scratching his head and puffing on a pipe while his son-in-law, modest test pilot Patrick, replaces the scientist's dead son and climbs into the experimental plane to prove that the envelope can be expanded.
It's an interesting scientific-military soap opera, acted with stiff upper-lip restraint by a great cast, but Lean's visual sense really comes into play in the aerial sequences which go beyond scientific interest to suggest an existential exhilaration in sheer achievement.