Gatwick Airport is set to spend a further £200 million on construction as part of the airport’s transformation scheme, which will include the upgrade of shopping facilities and the expansion of the north and south terminals.

The injection of cash will take the airport’s spending to more than £1.2 billion by 2021, and will take the airport’s spending since 2009 to over £2.5 billion.

Mayor of London, Sadiq Khan, unveiled the investment plans at an event at the airport, where he backed plans for a second runway at Gatwick, which he believes will bring “substantial economic benefits.”

The recently appointed mayor has previously spoken out against the proposed expansion at Heathrow, has said that a decision must be made quickly on the Gatwick proposition and urged new Prime Minister Theresa May to support the scheme.

Chris Grayling, who is the MP for Epsom and Ewell, which lies just 31 km away from the airport, was appointed Transport Secretary last week as part of Mrs May’s cabinet reshuffle, and he will now be tasked with the decision on whether to expand Gatwick.

However, he is yet to publically voice his opinion on the proposed expansion of either Gatwick or Heathrow, although it was reported in 2009 that he privately voiced concerns over the Conservative party’s opposition to Heathrow.

Meanwhile, it was revealed earlier in the week that Gatwick Express is the most delayed rail service in Britain.

In the last six months, over 8,100 services ran late between London Victoria and Gatwick Airport.

Govia Thameslink Railway (GTR), which is already under scrutiny after it recently announced its intension to scrap 341 Southern trains per day, operates the premium priced service.

The five worst routes in the UK are run by GTR, with the second worst service – the route from London to Brighton – operated by Southern, which saw 32.8% of its services (almost 35,000 trains) arrive late in the last six months.