Hang on - you can refuse a penalty fare and go to court, can't you?

No. When an inspector finds you with an invalid / no ticket he has
two options.

1. He thinks that you are deliberately avoiding the fare. He will
not issue you with a penalty fare but report your details to the
prosecution office who decide if there is enough evidence to take you
to court.

2. He decides to issue you with a penalty fare. Once he has gone down
this route then you cannot be taken to court for fare evasion as this
would be considered double jepody

So you can see that is either court or penalty fare but not both. In
the penalty fare case you can appeal to an independent adjudicator but
you will not get a criminal record whatever the outcome.