But the Biden administration is continuing to drag its heels on allowing Britons to travel to America – despite the UK now welcoming visitors from the US.

Industry sources said that Washington is not expected to reopen the borders until the end of November at the earliest.

The extended US ban on British ­arrivals means that Virgin Atlantic is once again facing the spectre of cash reserves running below the minimum levels required under its banking terms. The London float is understood to be conditional on routes to North America being open in both directions.

Virgin Atlantic sold two of its airlines earlier this year to raise £160m, and a cargo arm has brought in much-needed profits during the pandemic. However, City sources said that the float would be key in bolstering the airline’s reserves until transatlantic services return in earnest.

Sources close to the airline insisted that plans to list on the London Stock Exchange were well-received by institutional investors over the summer.

The carrier is working with bankers from Citi and Barclays to drum up ­interest. They added that the airline has limited its cash burn and was close to breaking even in two months during the summer.

Consent from lenders for a float is typically a formality but City sources said that some creditors are nervous about Sir Richard’s Virgin Group selling down its majority stake as part of going public.

They fear that if he the billionaire is left with less than half of the company, he will be less likely to step in and keep it afloat if needed. Sources cited the example of Virgin Australia, which the entrepreneur held a minority stake in when it collapsed last year.

Virgin Atlantic declined to comment.