Northern line extension to Battersea

From the longer Wikipedia page

The Northern line extension to Battersea is an extension of the London Underground Northern Line currently under construction from Kennington to Battersea in South West London, terminating at the redeveloped Battersea Power Station. The extension will form a continuation of the Charing Cross branch of the line. Two new underground stations will be built at Battersea Power Station and Nine Elms which will serve a new embassy district including, amongst others, the United States embassy and the Dutch embassy.

The extension is a partially privately funded project by the site developers, SP Setia and Sime Darby, with contributions from other sources such as the new US Embassy. Construction began in 2015, and the extension could be open by 2020. Both stations will be in Travelcard Zone 1.

Provision will be made for a possible future extension to Clapham Junction Station by notifying the London Borough of Wandsworth of a reserved course under Battersea Park and subsequent streets