Fairly obvious, I would have thought.
What we want is EE being allowed to use its 1800MHz spectrum for LTE. In return for this, they must be required to sell that 30MHz they are required to sell *right now*, and the sale process must be something transparent so that the other operators are not prevented from buying it if they want. Joint ventures between the other operators allowing them to buy it and build a shared network (so that everyone can offer 4G to their customers as soon as possible) once again should be explicitly allowed and indeed encouraged. (Such a shared network might run out of capacity fairly quickly, but hopefully by the time it does the individual operators will also have LTE running at 2600MHz and it won't be a problem). Somewhere in all this, we get rid of all restrictions that exist on what operators may use their spectrum for. (Once you own it, you may use it for anything you want).
Why has this not happened? It seems blindingly obvious.