In January 2019, it was announced that due to a variety of construction delays, the opening of the project would be delayed from December 2020 to 2021. In June 2019, it was announced that installation of track had been completed, and that an engineering train travelled the full length of the tunnel from Kennington to Battersea for the first time. By February 2020, construction of the extension was nearly complete, with platforms, escalators and the Tube Roundel installed in the stations. In the early spring of 2020, work on the extension was paused due to the COVID-19 pandemic. Work resumed at the end of May 2020 with social distancing and other mitigation measures. In July 2020, the roof of the Battersea station was handed over to the Battersea Power Station developer to allow their construction to begin. In late 2020, stations were energised and track traction current turned on. Subsequently, the first 1995 Stock train ran onto the extension over the 2020 Christmas period, marking the start of the signal testing period.
