That's not the way I remember it. As I recall, he was fired because his son caused a run on the bank; he couldn't get his tuppence back (to feed the birds), so all the other customers demanded to withdraw their savings, and the bank didn't have enough cash in the building to satisfy everyone. I think that's also a lesson which applies to modern times, i.e. irresponsible journalists could cause a bank to collapse if they urge everyone to pull out their money before it's too late, but it's quite different to what the BBC article mentions.
I've only seen the film, not the stage version, so has it been changed as it was adapted? If it has been changed, that's fair enough, but then it's not too surprising that the "period piece fable set a hundred years ago is grimly relevant to our troubled times", since this version was in fact written in modern times. Or is my memory just failing me altogether?