The escalating prospect of a Formula 1 race in London has prompted fresh concern for Silverstone amid its negotiation of a new British Grand Prix deal.
A grand prix in the English capital has been explored extensively by F1 owner Liberty Media and London mayor Sadiq Khan has previously stated it "should be possible to organise".
This has always been touted as an additional event to the British GP and originally slated by F1 sporting director Ross Brawn as a prospect "not slap-bang in the centre of London, but Greater London".
Silverstone is preparing to host the final race of its current deal after activating a release clause in its contract with F1 to avoid paying unsustainable hosting fees.
It has been negotiating a fresh contract but has become concerned by the emergence of an event in London's docklands as the favoured option for a separate race in the country.
The same area of London will host the final race of 2019/20 season of the ABB FIA Formula E series, which will return to the city at the ExCeL exhibition centre.
Autosport understands Silverstone was only recently been made aware of the extent of the progress of an F1 race in east London.
Though such a grand prix would be unlikely for some time, its emergence would present a threat to Silverstone, which is based just two hours north of the city.
Silverstone's fear is that the proximity of the events if both were on the calendar, and the narrow range of dates available to run them during the British summer, would hurt attendance and make hosting the British GP financially unsustainable.
While talk of an F1 race in London has been ongoing for sometime, Silverstone managing director Stuart Pringle told the BBC that F1 has admitted its desire to him "for the first time".
He added: "That's a material change because it's different to previous arrangements and Britain is not a very big island and it's a commercial concern."
Pringle said that Silverstone was "nearly obliterated" by the terms of committing to a new 17-year F1 deal back in 2009.
In recent years the British Racing Drivers' Club-owned venue has expanded its portfolio to try to create a business model that is not dependent on the British GP.
That has included nailing down events like MotoGP and a festival based around a new deal to host Britain's World Rallycross round (pictured above), plus non-racing components like the Silverstone Experience and a brand new hotel.
Negotiations between F1 and Silverstone continue ahead of the 2019 British GP, which will be held on July 14.
Last week, five-time world champion and winner of five British GPs Lewis Hamilton said a London race would be "awesome" and that it "wouldn't be bad to have two races in the UK".
However, he stressed the significance of not losing Silverstone.
"The UK is really amongst the foundation of what this sport is, and if you start taking away the legendary races, and it's all just new ones, you lose all the history and all the culture," said Hamilton.
"I truly believe that they've got to keep F1 in the UK, and particularly Silverstone.
"It's such an awesome track, such an awesome place. It's one of the biggest turnouts of the whole season.
"You can't turn your back on that."