Bates’ prison education

It may be just me but it seriously grinds my gears every time Bates says prison was an education after being jailed for snuffing out Vera. He already went to prison when Vera was getting light fingered with the regimental silver so surely he was able to cultivate his pick pocketing, document forging hobbies as part of that sentence?

Also his whole persona is supposed to be so sickeningly noble, surely he wouldn’t lower himself to learning this stuff? Makes no sense to me. Rant over 😂