Canadian Lance Stroll led the way for Mercedes-lookalikes Racing Point in British Grand Prix practice on Friday while Red Bull's Alex Albon crashed and brought out red flags.
German Nico Hulkenberg meanwhile signed on as Stroll's stand-in team mate after a busy 24 hours triggered by Mexican Sergio Perez becoming the first Formula One driver to test positive for COVID-19.
Stroll, whose billionaire father owns the team, lapped the former World War Two airfield with a best time of one minute 27.274 seconds -- marginally quicker than Max Verstappen's best effort of the morning for Red Bull.
Verstappen managed a 1:27.422 in a sizzlingly hot opening session when Stroll was third fastest.
The Dutchman was only 14th after lunch when he was blocked on his sole attempt at a quick lap.
Albon crashed at Stowe in the afternoon but still ended up second overall and played down the accident.
"We've definitely made a step as a team," said the British-born Thai.
"The car was hooked up straight away. I'm sure Mercedes are hiding quite a lot but as a car it feels well balanced."
Mercedes' six times Formula One world champion Lewis Hamilton was second and fifth in the sessions run in front of empty grandstands with spectators not allowed due to the pandemic.
The Briton, a six times winner at Silverstone, leads Finnish team mate Valtteri Bottas, sixth and third fastest in the respective sessions, in the standings by five points after three races.
Mercedes have won all three races so far this year.
"Quite a difficult day, to be honest," said Hamilton. "It's always windy here... that's actually a good thing about this track but it's made it really tricky today with the car. The balance is not as good as I'd like.
"It's not a disaster but it's definitely been a hard day of driving."
Ferrari had Charles Leclerc fifth and fourth but the Monegasque's team mate Sebastian Vettel was sidelined for the opening session after Ferrari detected something wrong with his car's intercooler system and decided to strip it down.
The German was then 18th after lunch, when Ferrari decided to change his car's pedals.
Hulkenberg, back for what may be two races, looked like he'd never been away after lapping ninth and seventh fastest respectively for a team whose car is subject to an ongoing protest over its legality.
"The last 24 hours have been a bit special, crazy and wild," said the German, wearing a spare pair of Stroll's overalls.
"At 4.30pm yesterday afternoon I got the call, took a plane here. Seat fitted until 2am tonight, 8am this morning into the simulator for an hour... so it was a short night but all worthwhile."
Alfa Romeo's Antonio Giovinazzi brought out red flags at the half hour mark after spinning at the exit to Becketts in the morning, leaving debris across the track.
Formula One said Perez was the sole positive from the latest batch of 3,909 tests carried out between July 24-30.
(Reporting by Alan Baldwin, editing by Christian Radnedge and Toby Davis)
