Airport expansion: Goldsmith; Valentine and Burns An MP who pledged to trigger a by-election if the Conservative Party went back on its pledge over expansion at Heathrow Airport said it was "not a new threat, it's on old pledge which I would honour." Zac Goldsmith told the Daily Politics that Tuesday's Davies Commission report was "not a U-turn, it's a big step towards a potential u-turn." He debated with ex-transport minister Simon Burns who denied Heathrow was the favoured option, but said it was "one of three-and-a-half options." Talking about capacity figures, Jo Valentine of the London First business group said: "We can't pretend there is not a problem at Heathrow." Green mayoral candidate: close London City Airport Airports Commission reveals expansion shortlist