If I'd used my pay as you go Oyster up to the maximum fare for the day, and then forgot to touch in for my next journey on the same day and got inspected, would I actually be guilty of fare evasion? Or would it be some other regulation I would be guilty of not obeying? Just curious, not planning on doing it...
Difficult to answer that unless you reveal more information about
1) Which cap you had reached (assuming that's what you mean)
2) Which train you were 'caught' on, and between which stations
3) Where your journey started, were the barriers open etc
In general I'd have thought you would be issued a Penalty Fare if caught in such circumstances rather than accused of fare evasion, but perhaps not under certain circumstances, but it is totally impossible to say for a hypothetical situation with no detailed info! So take the answer to be "possibly"!