This is a chance for Tube Lines and LUL to re-scope works. Both LUL and Tube Lines work out how much they think it will cost and cme up with a price. If they can't agree then the Office Of The PPP Arbiter comes in. He has already said that LUL must pay at least an extra £1bn.
A number of project costs have increased since Metronet went into Administration as contracts were cancelled or re-tendered.
What with their not being the money to do the Metronet upgrade and the Directors jumping the sinking ship at Tube Lines, PPP won't last much longer - then what!