That's right Havell.
It's that chapter that shows all the ultra-volence of Alex only as a phase of puberty really. Something he'd grow out off - just like everybody else (George did too - from his old gang).
The movie ending is
because the movie ends with Alex and the PM being the best of friends and Alex getting a nice well paid job as a compensation for what has been done to him. There's no talk about a new gang and Alex' changed state of mind... You know, when he realises that he SPOILS THE END OF THE BOOK!