Pressure mounted on Boris Johnson to approve the expansion of City Aiport, as a record number of passengers took to the skies this summer.

In July more than 400,000 passengers boarded planes from the capital’s business airport, an all-time high.

The figures marked a “big milestone in the history of the airport”, said LCY head Declan Collier.

“These record figures also underline that we must be allowed to grow,” he said.

“The £16 million plan to transform our Western Pier departure gates will provide huge benefits when complete in autumn 2016, but it is only a small step on the journey to improving our airport.

“It is critical that we are allowed to proceed with our City Airport Development Plan (CADP) that will deliver better infrastructure, more jobs for our local community, better facilities for our airlines, and a better passenger experience for our growing passenger numbers.”

LCY has mounted an appeal against the decision by the Mayor of London to refuse permission for plans, which include building a parallel taxilane and seven new aircraft stands.

The airport says the move would provide vital airport capacity, create 1,500 new jobs and generate £1.5bn annually for the UK economy by 2023.

City Airport has recently announced it is to be put up for sale at the end of the year.

Owners Global Infrastructure Partners, who also own Gatwick and Edinburgh airports, are seeking to make £2billion from the sale.