The station redevelopment, which is being led by Costain under a £400m deal with partners including NG Bailey and WSP, has been under intense scrutiny in recent years as work continued while Britain’s fourth busiest station remained open.

London Bridge’s concourse is part of the six-year redevelopment of the station that is due to complete in 2018.

When the concourse is built it will be the size of Wembley Stadium.

The redevelopment is part of Network Rail’s railway upgrade plan and the Thameslink programme.

London Bridge is used by 56 million passengers each year.

Network Rail’s chief executive Mark Carne said: “This is a big step towards the bigger, better railway passengers deserve.

“The opening of two-thirds of the concourse marks a major milestone in the redevelopment of London Bridge and, while there is plenty still to do, I am pleased passengers can now see the benefits beginning to come through.

“We are essentially rebuilding Britain’s fourth busiest station – the tracks, the platforms and the infrastructure which enables trains to run – while keeping the station open and doing our best to keep passengers moving.”