At a Q&A period following this film's world premiere at the Toronto International Film Festival, director Shane Meadows noted that the grim skinhead influenced upbringing of the 11-year-old protagonist was a true portrayal of his own childhood and many of the events depicted were drawn from his early life.
The poster on the wall (in the room in which Shaun has his hair-cut and puts on his new shirt) features six classic bands of the British Ska and 2Tone movement, and is from 1981's live vinyl album Dance Craze: The Best of British Ska...Live! The bands on the poster are Bad Manners, The Beat, The Bodysnatchers, Madness, The Selecter and The Specials.
The trivia item below may give away important plot points.
The feud between Shaun and Mr. Sandhu is strikingly similar to a scene from Cracker: To Be a Somebody: Part 1 (1994) in which the main villain, Albie Kinsella (played by 'Robert Carlyle') felt wronged by a Pakistani shopkeeper and later returns to the shop as a skinhead to take revenge. In both cases, the word "Paki" is used frequently and the shopkeeper is threatened with a stabbing weapon, only while Albie kills the shopkeeper with a bayonet, Combo does not kill Sandhu with his machete.