Did we ever find out what happened there?
Yes. I contacted FCC. FCC customer services agreed an itinerary being shown makes the ticket valid. I was assured that they'd never take anyone to court over this.
Well, they did, but withdrew at the last moment when they realised the defendant had proper legal representation and was going to win the case.
Costs were awarded against FCC, which I understand were not a trivial sum.
Ultimately it'll be taxpayers who pay for such blunders, due to the way rail franchising works. We effectively subsidise TOCs to wrongly prosecute people and we pay the price when they get it wrong. Lovely.
If anyone is prosecuted by FCC, and is in the right, then make sure you get yourself good legal representation. (If you are in the wrong, try to settle out of court!)
I don't know the outcome of each case posted here, because not every person gets back to us. In some successful cases the person who won does not want to publicise the fact, which I will of course respect, so I can't always reveal the outcome. But in this case the customer involved in the Brookmans Park/Hatfield case is happy for me to reveal the outcome.