Transport for London will this month present a business case for an extension of the Bakerloo line to the Treasury in advance of the Government spending review due to be published later this year.
Cllr Mark Williams, Southwark's cabinet member for regeneration and new homes, this week insisted that an extension with two branches through Southwark – one via Old Kent Road and another serving Camberwell and Peckham – was still possible.
"Current forecasts suggest that an alignment via Old Kent Road would have the strongest business case, but an alignment via Camberwell also shows a very strong case, well in excess of TfL's required threshold for investment," said Cllr Williams.
"The Old Kent Road option will have a major impact on enabling the delivery of new homes.
"The Camberwell and Peckham option builds on the regeneration of the two town centres already under way and provides a much needed public transport link for local residents."
Speaking at council assembly this week, council leader Peter John said that the decision on whether to build one branch or two would ultimately be out of City Hall's control.
"The reality is that it is a decision that is going to be taken probably by the Treasury, because the Treasury doesn't trust London government to decide on infrastructure projects for itself," he said.
Southwark Council says that TfL will this month submit a business case for the Bakerloo line extension to the Treasury as part of the Government's spending review which is due to be published in the autumn.
Isabel Dedring, London's deputy mayor for transport, recently offered an insight into her thinking on where the tube link should go.
Speaking at the London Assembly's regeneration committee on 2 July she said: "Historically what we would say is: 'here is the perfect transport route for the Bakerloo line extension' and then we would say 'right, so what is going to be the impact in terms of planning?'
"South London is so deprived of tube connections that you could put the Bakerloo line extension virtually anywhere and you would get a fantastic impact in terms of transport.
"From a transport perspective it doesn't really matter where the Bakerloo line extension goes, but it does matter from a regeneration perspective.
"We are trying to look at where we get the biggest regeneration impact ... in terms of delivering new homes and delivering growth areas.
"Once we've identified that corridor, that is where we will put the Bakerloo line, which is quite different from the way transport infrastructure is historically planned."
Alex Williams, TfL's director of borough planning, confirmed that the Bakerloo line extension proposal enjoys strong political and popular support in Southwark and Lewisham, but in Bromley the picture is more nuanced.
"The local residents are very supportive of the scheme within Bromley; the local authority is very opposed to the scheme within Bromley," he told Assembly members.
"I am not entirely sure how we will square that particular circle.
"It's an ongoing line of political debate with deputy mayors here [at City Hall] and the local authority.
"It's a very odd disconnect there, where you've got very clear support for that service locally but the local authority don't agree with the response."