BAR's hopes of a morale-boosting podium finish in front of thousands of British fans began to unravel before Jenson Button had left the grid.
Technical director Geoff Willis had met his former Williams colleague, Adrian Newey, now his opposite number at McLaren.
"He told me he was sleeping much better," Willis revealed.
Kimi Raikkonen's blistering getaway from pole position - grabbing a lead of nearly four seconds on the first lap - revealed the reason for Newey's new-found peace of mind.
The McLaren MP4-19B performed like a potential race winner which spells trouble for Button's dreams of a first victory in 2004.
McLaren are closing in on BAR
"We came into this race expecting a lot more than we've been able to deliver," admitted the fourth-placed Briton.
"Our pace showed that we weren't as quick as we were at the start of the season.
"Somehow we've managed to drop behind which is very disappointing, particularly in front of our home crowd."
Team boss David Richards echoed that sense of anti-climax.
But he was keen to emphasise that BAR had pulled away from their rivals in the constructors' championship, consolidating third place.
Button has moved five points further ahead of Renault's Jarno Trulli in the drivers' standings.
"Failing to score a podium for the fans out there who were cheering us was a disappointment," Richards said.
"But we will certainly be giving them something to cheer for the remainder of this year and when they come back [to the British Grand Prix] in 12 months time."
Whether that includes the team's first victory - for Button or Takuma Sato - remains in doubt.
Newey told the BBC that the MP4-19B at Silverstone was still not the complete package.
"We'll be testing at Silverstone this week and if all goes well then we could see new parts ready for the next race [at Hockenheim]."
If Raikkonen and David Coulthard are given the machinery to fight at the front, BAR face a severe challenge to maintain their eye-catching progress for the remainder of the season.
"If we take Raikkonen out of the equation then we would have got what we wanted," said Willis.
"But Raikkonen was quicker than we expected and we need to understand what they've done on top of the clear development they've made.
"Our rivals have had their ups and downs but it looks as if McLaren have had their down and now they're on the way back up, so we could find ourselves fighting very hard to keep our third place.
"In some ways we've been surprised that we've had a clear shot at being at the top of the Michelin runners.
"It's [McLaren's comeback] something we've been expecting but maybe we were lulled for a few races."
Willis is also concerned at the team's inability to force both cars into regular point-scoring places.
Sato started eighth but after an initial charge he got swallowed up among the also-rans and came home 11th.
Initial inquiries absolved Sato from errors, but the computer telemetry revealed no obvious failings.
"There is no fundamental fault with the car," assured Willis.
"It's just that it needs to be improved everywhere - more downforce, better weight distribution, more power and more consistent tyre wear."
For Jenson Button, that development work cannot start soon enough.
"We've got a lot of work to do now ahead of the German Grand Prix in two weeks," he said.
Button may not have welcomed McLaren's return to form, but renewed competition for Ferrari can only be good for Formula One.