The proposed tunnel with 13 stations would run from Wimbledon in the southwest via central London to Alexandra Palace and Tottenham Hale and cost around £12bn to complete.

The task force, which was set up by the London First group of business leaders, wants the mayor of London to bring forward detailed planning and consultation on Crossrail 2 to late this year or early in 2014 with a view to starting detailed design and parliamentary approval in 2015. However, construction is not expected to start until 2026 with completion envisaged in 2033.

Nevertheless, the report states: "We must not repeat the mistakes of Crossrail 1 and spend 40 years planning and generating support for a scheme needed within 20 years. Serious work must begin now." Network Rail and the mayor of London have already declared their support for the project.

Crossrail 2 will relieve congestion on commuter services into London Waterloo and London Underground's Northern, Piccadilly and Victoria lines, and will also help to disperse passengers arriving at London Euston, the terminus of the planned HS2 high-speed line to Birmingham and northern England. Over the next 20 years, employment in London is expected to increase by 700,000 while the population is forecast to rise by 1.5 million to 10 million. Crossrail 2 would also cut journey times substantially by providing through services from places such as Kingston and Surbiton to central London.

The task force says that Crossrail 2 will not require a significant increase in spending as the Thameslink and Crossrail 1 projects will have been completed by the time construction starts on Crossrail 2. Indeed, if Crossrail 2 does not go-ahead there would be a substantial cut in railway investment in London.Crossrail2map