A graduate who tweeted advice which can help rioters avoid being arrested is the son of two prominent Jewish socialists.
Jacob Bard-Rosenberg is the son of David Rosenberg, one of the founding members of the Jewish Socialists' Group in the 1970s. Julia Bard joined the group in 1983 and the couple married two years later.
They are still active in the organisation, which supports campaigns including the Stop the War coalition and European Jews for a Just Peace, a group which recently attempted to send a flotilla to Gaza.
Mr Bard-Rosenberg, who has a twin brother, has been outspoken about his left-wing views in the past. As rioting broke out in Tottenham, and then elsewhere, the former Cambridge University student, who is now based in London, discussed on Twitter ways rioters may be able to avoid arrest.
He wrote: "For anyone heading to places where riots are: 1) Mask up. Properly, not just a hood. 2) Bindmans solicitors if you get nicked." He also posted the solicitors' telephone number.
When the Metropolitan police began publishing pictures of suspected rioters, he added: "If you're pictured get rid of your clothes and change your appearance."
The 25-year-old, who also studied for a master's in cultural and critical studies at Birkbeck College, wrote in another post: "The aggressors are the state and bankers; the victims are the poor."
And when the clean-up efforts began, he added: "Stop with the disgusting Big Society politics. As I said, #riotcleanup will just push down the price of labour."
Both he and his brother are part of a group of bloggers for a left-wing intellectual site called "The Third Estate".
When the twins celebrated their barmitzvah, the event involved poet Michael Rosen acting as MC and a Marxist magician for entertainment. The simcha was held in the banqueting suite of the Trades Union Congress.