The British government confirmed a 14-day quarantine measure that will be applied to all travelers entering the country from June 8, but there has so far been no sign of an exemption for F1.
As it stands, the measure implies that the British Grand Prix double-header at Silverstone will not be able to take place at its tentative end of July and early August dates, although UK authorities have given no indication of how long the quarantine will remain in force.
Home Secretary Priti Patel justified the UK's decision to implement the new COVID-19 measure "to keep the transmission rate down and prevent a devastating second wave," she said.
However, Formula 1's response to the news on Friday still leaves a glimmer of hope.
"We have been working closely with government on the implications of the policy for Formula 1 and Silverstone and those discussions are ongoing at this time with the aim of finding a solution with safety as our first priority," read a statement from F1.
The sport is scheduled to raise the curtain on its season behind closed doors on July 5 at the Red Bull Ring in Austria, with a definitive green light expected next week by the local government.
If Silverstone cannot host the third and fourth rounds of the world championship, F1's contingency plan involves staging races at Hockenheim in Germany or at the Hungaroring, or eventually at both venues, meaning British teams would remain out of the UK for over a month before returning to base and submitting to the 14-day isolation period.
Formula 1's chiefs are still hopeful of building at least a 15-race calendar but plans remain tentative, at the very best, as countries deal on an individual basis with easing measures.