...it will in fact be used at the same time as the new runway.
This isn't possible in under instrument conditions because the runways are too close to be operated 'independantly'.
Take-offs from the existing runway 26 (R) will still have to turn left to avoid Luton and would immediately conflict with take-offs or overshoots from the new runway (26L).
As for the idiot that bought a house at Breachwood Green, well presumably he was brain-dead when he bought it!!