hi and thanks for your responses... I've already written a letter and offered to pay the penalty fine several times (once when I was being cautioned and every time in my subsequent communication with the prosecutor)
it just seems like they're determined to prosecute - which technically they can because i did get on without a ticket. However, what really gets me is their inconsistency: if they prosecuted everyone that would be fine but some people get away with a penalty fare, some people are allowed to settle out of court with cases much worse than mine, but me - because he's taken a dislike to me, I'm being prosecuted. Slightly unfair I think...
I guess that's what happens when you have power: you can't help but play God with people's lives.
edit: oh and I don't travel all the time to zone 6 hence the zone 1-2 oyster