I have always believed that option 2, for the extra runway to be built south of the LGW airport, will be the one chosen.
The option for the runway that has Horley as an undershoot is a red herring that can be discarded in reaction to the opposition groups that are bound to be set up.
One of the opponents predicted twice the traffic, twice the polution and twice the noise. In fact I suggest that they will achieve twice the traffic and the noise and polution will be significantly reduced thanks to the reduction in holding prior to departure, stacking before landing and being able to fly cleaner approaches.
Perhaps those of us in the LGW area who believe in the benefits that 26L will bring should form our own pressure group.