All but essential and safety-critical activities on the 25km super sewer were put on hold at the start of the coronavirus lockdown.

In recent weeks, a series of detailed safety reviews has enabled contractors to implement measures to protect workers and the wider community.

The measures fit within the Construction Leadership Council’s guidance and official public health advice, and include social distancing and personal travel plans.

Work is now taking place on 21 Tideway sites, including underground tunnelling from Fulham to Acton and tunnelling of the smaller Frogmore Connection Tunnel in Wandsworth.

Around 1000 staff are back working on site, with the majority using private transport, or walking or cycling.

Tideway CEO, Andy Mitchell, said: “It was absolutely right that we paused our activity at the start of the pandemic.

“Only by planning very carefully what activities are safe are we getting our teams back to work.

“Our measures have been developed with our workforce and contractors and are being introduced after detailed safety reviews of every one of our sites.

“The measures mean we are able to get more of our work back up and running, safely, minimising delays to this vital project and contributing to wider efforts to support the UK economy.”

He added: “Those who are travelling by public transport will be avoiding peak times and following public health guidance.

“Tideway will be keeping all activities and the new measures under review, in collaboration with contractors and the wider workforce.”