Actually such a petition is likely to succeed, given the nature of Chris Davies' crimes. People hate expenses cheats.
Probably if he'd gained from it.
But given that he was stupid rather than thieving ...
He did not gain directly from it, but still knowingly broke the law: this was not a legal slip-up. To be honest, I'm not sure why he did it. What could he stand to gain, besides the minimisation of the public impression of his expense claims? Or was he not aware that he was able to gain the £700 legitimately? Either way, it doesn't seem worth it to me, but neither did Onasanya's cheating, and arrogance still won the day there. I reckon the presumptuousness alone would be enough to fire up 10% of his constituents.
A reminder that Denis MacShane was jailed for fraudulent expenses claiming, when he could have claimed legitimately for everything.
That reminds me of the Father Ted episode where Ted gets a lift from John (I killed JR) who promptly stops and holds up the post office with a shotgun. He claims that it was his money but he couldnt do with filling in the forms.