"The most signed e-petition on the No 10 website is one calling for convicted rioters to lose benefit payments."

The real problem of this is that it is essentially retrospective. On the assumption that we, if not they, hold the law important, this should not apply to offences already committed. I agree with this quotation from 'A Man for All Seasons':
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William Roper: So, now you give the Devil the benefit of law!
Sir Thomas More: Yes! What would you do? Cut a great road through the law to get after the Devil?
William Roper: Yes, I'd cut down every law in England to do that!
Sir Thomas More: Oh? And when the last law was down, and the Devil turned 'round on you, where would you hide, Roper, the laws all being flat? This country is planted thick with laws, from coast to coast, Man's laws, not God's! And if you cut them down, and you're just the man to do it, do you really think you could stand upright in the winds that would blow then? Yes, I'd give the Devil benefit of law, for my own safety's sake!

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Yes, if it is Parliament's will, make stopping of benefits for rioters from today onwards one of the possible punishments. But changing punishments after the crime is a very dodgy practice...