Well, it seems knowingly poseurish in a grad student kinda way:
Mr Small tries a succession of jobs for which he is woefully mismatched - they are all manifestly too big for him. He lacks the basic knowledge and skills to hold down any of the occupations he attempts. Does Hargreaves here break from his usual social conservatism with a damning indictment of an education system that is not adequately preparing the workforce for increasingly skilled and mechanized labour? And in this does he further express his frustration at how his own fictional potentialities have been manacled and constrained by this state of affairs?
Indeed, Hargreaves himself seems to give up on Mr Small - in a wry narrative flourish of course. Beneath the surface positivity of the ending, we at best encounter stoicism, with a definite undercurrent of fatalistic dread at what the very near future holds. The shadow of the impending Thatcher years is already falling across the world of the Mr Men. If Hargreaves has deprived him of revolutionary socialism in Mr Uppity - or even the more modest protection of the centre-left - there is nothing Mr Small can do but passively accept his situation. Mr Robertson, a literary personification of statutory intervention, is ultimately powerless to help him. The collective sentiment of the workers - embodied by a friendly postman - offers nothing practical, just sympathy. The only job that Mr Small proves fit to do is recount his story to the author. (Contrast this with the earlier Mr Bump, who successfully finds a job compatible with his idiosyncrasies as a character.)