Ok, I'm not going to quote individual pieces I'll try and explain in one fell swoop. By 'new' employees it is meant post 2003/4 when the part privatisation thing properly kicked in. The employees in question are metronet workers (now in administration) that are about to go back under the control of TFL.
When metronet took the reigns of that part of the underground (the trains and stations remained under public ownership) they moved the goal posts in terms of some conditions for new employees in order to 'cut costs' (increase profit margins).
Since the privateers have now creamed the system, gone bust, and crawled back to their still healthy umbrella companies, the RMT wanted the negative side of their legacy to be, erm, abolished?
There's no need for apartheid in the workplace. Nobody is suggesting that these tube workers are hard done by. But the share-holders screwed the company into the ground. If they'd have been building cars then it would have gone the same way as rover. Fortunately to the workers, London needs a continued transport system.
All that is being asked is that the workers continue to have the same benefits as before greed was brought into the equation and new (post 2003/4) workers can enjoy those benefits too.
Hope that answers all queries. Nice to see you're still up though!