Its rhyming slang. Pretty much think it stems from a large number of british soldiers coming home from WWII to find their wives/girlfriends/sisters fallen prey to less than immaculate conception courtesy of randy GI's
Glad you liked football factory, having known a few hoolies over the years, I recognised truth to a fair few of the characters in that movie. Its still romanticised to hell, but its pretty close.
Next stop in your fictional education should be 'I.D.' and 'The Firm' - both great movies on the subject, but not as much fun