Okay, thanks for the explanation.
Well, it actually seems to me that this is the train companies error really!
What a stupid system that someone 'forgets' to swipe in [which I have also done numerous times legitimately] but are then only charged the maximum fare of £7 when it should actually be £20 from the start of the train line.
When I have done this and been charged £7 I should have actually paid £3 and so am overcharged £4.
I know this particular chap didn't keep forgetting to touch in [to the tune of £40,000] but I bet that's how he initially discovered the loophole. I wonder how many other people have done the same?
Again, I personally fail to understand the extreme outrage on here. I must also be a devious, greedy and immoral person [oh well].