Perhaps BAA should buy EI, shut down the LHR ops, sell the rest, and cancel the LHR slots to create a buffer in the movements schedule to cover inclement weather, radar outage, strike etc. And pigs will...
But..maybe BA should buy EI and negotiate the cancelation of the slots to create the buffer, which would enable BA to carry on ops (without inconveniencing their customers - the basic requirement of pax) in the event of said disruption.
And hey! No 3rd runway needed!