A spokesperson for Crossrail Ltd said: “A member of the Bond Street team has tested positive for COVID-19 while on annual leave.

“In line with Public Health England guidance, the individual’s immediate colleagues have been asked to self-isolate.

“As a further precaution the site has been closed today (19 March) to allow deep cleaning of the areas used by this operative team.”

A Costain/Skanska joint venture is main contractor on the site

One site worker told the Enquirer: “Obviously everyone is quite concerned by this and morale has been down over the past weeks due to the uncertainty where everyone stands with their jobs.

” A lot feel the main contractor and companies are not doing enough for the wellbeing of staff on site.”

The news came as Crossrail Chief Executive Mark Wild gave an update on the impact of coronavirus on the project.

As many office staff as possible have been told to work from home while Crossrail looks to keep its construction sites open.

Wild said: “Crossrail Ltd is a subsidiary of Transport for London and aligned with TfL’s policy and procedures for the management of the coronavirus risk.

“As we have done throughout, we are following the advice of Public Health England – with immediate effect this week those who can work from home will do so.

“Essential and business critical work will continue across the Crossrail programme, but our priority is to keep our people safe and limit movement across our sites.

“While we are doing everything we safely can to keep the programme on track, COVID-19 will have an impact – it’s too early to tell what that impact will be.

“We are doing everything we can to support our contractors during this difficult and challenging time and we will do what we can to keep individual sites open and productive as best as we can.

“Our arrangements remain under constant review and we are liaising closely with our Tier 1 contractors and their supply chains to ensure that the Crossrail programme continues to be delivered safely.”