One of the central themes of this important play is that of alienation and loneliness, that is of course presented to us in the character of Jimmy Porter. In particular, Osborne uses him as a mouthpiece to rant about the inequalities of British society in 1956. Even though he received a good education, the fact that he attended a newer (and therefore less prestigious) university meant that he felt he was prevented from playing any significant and meaningful role in society.
Those kind of privileged positions are only available to those who have been brought up in the "right" kind of families and attended the "right" kind of educational establishments. The famous British "stiff upper lip," which refers to the Englishman's distaste of expressing any emotion, is of course expressed in the character of Alison, Jimmy's wife, who seems unable to engage fully with her emotions, in spite of Jimmy's encouragement for her to do so. Note what he says at one stage about this trait of hers:
My heart is so full, I feel ill--and she wants peace!
He rants and raves in the attempt to produce some kind of reaction, but all in vain. Jimmy is therefore a character who is profoundly at odds with society and the kind of environment in which he has been brought up thanks to his class and life chances.