As for the rent still being paid, I read it on another website but for the claim to succeed he would have had to have abided by his contract anyway, tenancy contracts are generally pretty solid in that respect, so he must have been paying otherwise there isn't a chance he would have got anyone to represent him in court.
Chances are he is on a no win no fee basis, and solicitors taking on these claims have a specific risk assessment and generally if there is a less than 61% chance of success they wont take on the case. If he hadn't been paying there wouldn't be anywhere near that high a chance of success. I can't find the page I read it on now but I'll trying to find it.
Here is the page that said he used public money to fund his case though, implying legal aid.
Rapist Sues Landlady From Jail; Wins Damages