British Prime Minister Boris Johnson said on Monday he would try to find a way to honour his promise to oppose Heathrow airport expansion by lying down in front of bulldozers but that it might be difficult for him. The British parliament has approved an expansion plan for Heathrow, including building the first full-length new runway in the London area for 70 years, but the plans are being challenged in the courts. Before he won the top job, Johnson opposed Heathrow expansion and promised to lie down before bulldozers to stop it.