4 ideas
A narrator who records events faithfully but interprets them wrongly lets the reader see what the narrator cannot. The comedy and the pathos both come from the gap between what is written down and what is understood.
His unemployed father takes up with Doreen 'Stick Insect' Slater, and his parents later reconcile briefly. Meanwhile he chronicles his spots, his love for Pandora Braithwaite, being bullied by Barry Kent, and caring for the elderly Bert Baxter. Family breakdown and 1980s unemployment are seen entirely through a child who treats his acne as the bigger crisis.
Adrian announces himself an intellectual. The stance works as armour: claiming cultural superiority protects a vulnerable teenager from how ordinary his humiliations are, and his parents' crisis. The gap between pretension and competence is the source of the humour, and a portrait of how identity is tried on before it is earned.
The book sets the royal wedding, the Falklands War and mass unemployment beside Adrian's worries about the size of his 'thing' and his spots, often in the same diary entry. The point is that ordinary people meet national history through its effect on daily life: a day off school, a dad on the dole. They do not experience it as grand narrative. Political opinions, like Adrian's hostility to Thatcher, are adopted as badges of identity as much as reasoned positions.