('Brit') a family 'on benefits' [=('US') 'on welfare'; receiving money from the government because of a low income or lack of income]
Since he owns the land, he thinks he should be free to use it 'for his own benefit'. [=in a way that is helpful to him]
He might be lying, but we have to give him 'the benefit of the doubt' and accept what he says for now.
(..) ...and then he got himself knifed at Boston City Hospital. I believe it's been in the papers. You seem quite happy with that result. It's a fucking result. Yeah, but cui bono? Who benefits? Cui gives a shit? It's got a frigging bow on it. I think you are a cop, my son. - Where's your license? (..)2006 The Departed