OFT says that in 2008 the total market for private healthcare was estimated to be £5.5bn. They said that the NHS paid 23% of that or £1.3bn. Monitor says that in 2010 £252m of the income of Foundation Trusts (1.1%) was from private patients. It looks to me that so far private healthcare is "winning" by over a billion pounds per year.
So here's a radical thought. Rather than yet another upheaval in the vain attempt to try and get more of the leprechaun gold that is private patient income into NHS hospitals, why don't we just stop paying private hospitals to do NHS work? The NHS could do what it does well: cost effective, comprehensive, universal healthcare; the private sector can then do what it does: deep-pile carpet healthcare for people with leprechaun gold. And the NHS will be £1bn better off.