Transport for London commissioner Sir Peter Hendy has said that a southern extension of the Bakerloo line could be completed within the next 15 years - a decade earlier than City Hall predicated last summer.
"We ran a consultation between September and December 2014 on the principle of extending the Bakerloo line to the south and will publish a full report at the end of March," Sir Peter Hendy wrote in his report for this week's Transport for London board meeting.
"Work is under way to update key elements of the costs, refresh the business case, and investigate a number of alternative route options suggested via the consultation.
"Subject to feasibility, funding and powers, an extension could be delivered by 2030."
As political support for a Bakerloo line extension has grown, the timescale for delivering the project has shrunk.
TfL's consultation documents last autumn said that "completion is estimated by the early to mid 2030s" whilst last summer's London Infrastructure Plan gave an indicative date of 2040.