LONDON (Reuters) - Formula One bosses want Silverstone's owners to do their negotiating in private as both sides try to keep the British Grand Prix circuit on the calendar beyond next year.
Some 140,500 fans turned up for world champion Lewis Hamilton's home race on Sunday, a crowd unlikely to be beaten anywhere else this season.
However, the threat of 2019 being a farewell to the former World War Two airfield that hosted the first world championship race in 1950, and is a home grand prix for most teams, remains real.
Silverstone activated a break clause in 2017 for their hosting deal to end next year unless better terms can be negotiated.
"I'm sure we're going to find a solution with Silverstone because we cannot leave this behind," Formula One's managing director for motorsport Ross Brawn told Sky Sports television on Sunday.
"The frustration is the negotiations are taking place in public," he added.
"Every circuit we deal with, we do it quietly and get on with it, but for some reason Silverstone chooses to make everything public, which causes more difficulties. But we'll find a solution."
Silverstone is owned by the British Drivers' Club (BRDC), whose original deal was agreed with former F1 supremo Bernie Ecclestone.
The promoter's fee for hosting the race increases by five percent annually, which means it grew from 11.5 million pounds ($15.31 million) in 2010 to 16.2 million pounds in 2017. By 2026, it would have risen to 25 million pounds.
BRDC chairman John Grant told a news conference last year, after the circuit racked up multi-million pound losses in 2015 and 2016 despite huge crowds, that the current contract was "not financially viable".
The way in which the break clause was announced and subsequent briefings did not go down well with Formula One's new owners Liberty Media, who have taken a very different approach to Ecclestone's.
The U.S.-owned company, with Chase Carey leading their Formula One management, have a policy of keeping out of the spotlight when it comes to contracts and talks with possible new venues.
Silverstone is not the only circuit seeking revised terms since Ecclestone's departure, with Germany's Hockenheim wanting to remove the financial risk from its contract and Azerbaijan keen to pay less.
Silverstone, which has good traffic access, is seen as the home of British motorsport but a London Grand Prix has also been mooted periodically.
"There is a desire within Liberty to see a street race in London and in an ideal world we would be fortunate enough to have both," Red Bull boss Christian Horner told reporters last week.
"But competition on the calendar is extreme and it is difficult to see two British Grands Prix."
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(Reporting by Alan Baldwin; Editing by John O'Brien)