By marginalised I meant that they are unable to participate in any struggle to balance the equation. They lack the cohesion and solidarity effectively to withdraw their labour, and many of them are anyway on the fringes of the black economy, living in fear for being deported or having their meagre benefits stopped.
The Trades Union movement was a product of the traditional capital/labour equation, but I see precious few union leaders today making a genuine effort to help the underclass, so keen are they to trumpet their bourgeois credentials. In that sense, the underclass is marginalised and forgotten, even by the Left. But it is among them that the class struggle should be being fought - and sod the fishknives!