Ahead of a crucial early evening vote on the airport’s new runway, industry leaders called on Westminster to end years of wrangling by voting in favour of the plan. Conservative MPs were on a three-line whip to back the plan, with 40 Labour MPs expected to join them — helping it gain approval. If the SNP’s 35 MPs vote against, the margin could be tighter. Many in the City are keen to press ahead, with Brexit’s potential impact on trade looming large.