I am less confident about this. The definition of a ticket in the NRCOT seems to me to only include a contactless card described as being valid for travel on their services. There is at least an argument that a contactless card ceases to be “a ticket” when you leave the zones. Though that could go either way. Indeed, whether the OP was asked for a ticket or not is not made clear.Byelaw 18(2) of the Railway Byelaws makes it an offence to fail to hand over a ticket for inspection. It does not require that the ticket be valid, merely that you hand it over so its validity (or lack thereof) can be ascertained. This offence is not made out, provided you proceeded to proffer your bank card when asked for a ticket.
I am even less confident about this. Once the OP chose to travel past the validity of contactless cards and was challenged, the fare for his journey became the Penalty Fare. Declining to pay a Penalty Fare or any part thereof is prima facie evidence of intent to avoid payment.Section 5(3)(a) of the Regulation of Railways Act 1889 makes it an offence to travel on the railway without previously having paid the fare, if you intend to avoid payment thereof. There is no way this offence can be made out, since not only would you (as indeed occurred) be charged a maximum fare if you didn't tap out at a TfL reader, but there are barriers at Hatfield and accordingly there is no way you could have 'gotten away' with trying to use contactless. There is no strategy of fare evasion where using contactless beyond the boundary works.
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The specifics of whether an offence has been committed will, however, depend heavily on what was said and done at the time the OP was challenged. There is every chance of a successful defence by raising reasonable doubt.