[[WMG: Preston walking out was a publicity stunt.]]
During one episode Simon mentions that the BBC haven't received permission to show Paris Hilton's biography, which means that they must have obtained permission to show Chantelle's, therefore Preston/his PR people could have found out and planned accordingly. Also he says it was between walking off and assaulting Simon, and most people also have an "insult" option.
* Interestingly his apology was a few months after it was announced that Simon was leaving, making it likely that he really was angry at Simon, and the apology was a publicity stunt.
** Since the apology was as he was releasing a new single, both could be true. The walk-off was to get Preston more attention and the apology was to lose his "twat who walked off Buzzcocks" image.