Selling 2 London airports and 2 Scottish airports is the way to go.
BAA are saying that they expect the Competition Commission to say they are to sell at least one of STN and LGW, but possibly both, and
one Scottish airport, either EDI or GLA
BBC NEWS | Business | BAA expects forced airport sales
The main problem, apart from the stranglehold across the South East and Scotland, is that they can't focus on more than one major project at a time. And with Heathrow East, a third runway and possible T6, they can't really do the modernisation thing at their other UK airports!
...can only focus on one development project at a time, causing capacity problems.