The drama of a new £12  billion north-to-south train link across London gets a step closer this week as public consultation over “Crossrail II” ends on Friday.

Backed by Mayor Boris Johnson, Transport for London (TfL) wants to build the line between Alexandra Palace in the north-east and Wimbledon in the south-west, passing through Islington, Piccadilly, Chelsea and Clapham. The entire journey would take just over 30 minutes.

A more ambitious option would see the line extended beyond the M25 into Hertfordshire and Surrey.

The Government has shown cautious approval for the scheme — which would boost demand for homes along the route — by committing £2  million to a feasibility study.

And consultation into the plan, which should ease congestion on the Victoria, Northern and Piccadilly Lines, has received broad support from local groups – although the proposal has sparked numerous extra demands.

Surrey County Council is demanding the line is extended to Shepperton, Epsom, Hampton Court and Chessington, in order to relieve desperately overcrowded commuter trains into London. Haringey Council is pressing for an extra station stop at Tottenham.

The plans for Crossrail 2 include a stop at Angel Station but Islington Council is backing a second local station, at Essex Road, currently served by overground services to the City. If approved the plan would give residents a direct link to the West End for the first time.

A report on the proposal will be presented to the mayor later this year, but due to the complexity of the project TfL says it is unlikely to agree a route until 2016.

New and improved train services can have a dramatic impact on local property prices. Crossrail 1, the east to west rail link due to open in 2018 will, it has been predicted, hike property prices around its stations in London.

Jones Lang LaSalle, the investment management firm, recently forecast property growth of up to 19 per cent (over and above general London growth) in new homes around Crossrail stations over the next five years.

As things stand, the Crossrail 2 proposals could have a similar impact on areas such as Alexandra Palace, Turnpike Lane, Seven Sisters and Tooting.