Ahead of today's opening session the air temperature is 23 degrees C, while the track temperature is 40 degrees. It is a gloriously sunny and warm day... a rarity, it must be admitted.

In terms of upgrades, Red Bull has a new Front Corner, Mercedes a new Front Wing and Front Wing Endplate, Alpine a new Front Wing and McLaren a new Front Wing, Nose, Rear Corner and Rear Suspension.

At Alfa Romeo there's a new Floor, Floor Fences, Diffuser, Rear Corner and Rear Suspension, while Aston Martin brings a new Front Wing and Rear Corner.

Haas has a new Front Suspension, Front Corner and Beam Wing, while AlphaTauri has an updated Floor, Floor Fences, Floor Edge, Diffuser, Coke/Engine Cover, Rear Suspension, Rear Wing and Beam Wing and Williams a new Front Wing and Rear Wing.

Ferrari is the only team with no upgrades, having introduced a new floor and front wing last weekend,

As ever, while some teams are talking up their chances others are playing them down. Haas fears that its tyre deg issue is going to be major factor, while Charles Leclerc fears the flat, windy nature of the track will compromise his team.

Depending on how you view it, once again a couple of teams have opted for special liveries, among them Williams, which is celebrating its 800th Grand Prix and McLaren, which is featuring its iconic Google Chrome look.

The lights go green and Albon leads the way, followed by Alonso, Perez, Russell and Stroll.

As more cars emerge it's a mixture of hards and mediums.

"I've got limp home, I've got limp home," reports Stroll.

"I'm really on the nose through 1," says Russell, who subsequently posts the first time of the weekend (33.471).

Sainz, Hamilton, Magnussen and Leclerc all go quicker, but then Verstappen bangs in a 30.443 to go quickest by 1.220.

Hamilton improves but remains 0.979s off the pace. He and Verstappen are on hards, while Leclerc is on mediums.

Verstappen is told to cool his tyres.

Seemingly there are new power units for the Mercedes pair, Russell, Hulkenberg and de Vries.

Stroll (mediums) goes second with a 30.979 but remains 0.536s off Verstappen's pace.

"There is zero grip," reports Verstappen, "it's getting worse and worse." Despite which he goes quickest in S1, and then again in S2. At the line it's 29.863.

De Vries spins at Turn 7 but is able to continue.

15 minutes in and still no times from Albon, Alonso, Piastri, Sargeant or Zhou.

"Xavi please, not in the corners," urges Leclerc as he is given a raft of instructions.

A 30.814 sees Sainz (mediums) improve to second however he remains 0.951s off the pace.

"It's just like driving on ice," complains Verstappen. Hamilton is also unhappy with the seeming lack of grip.

A 30.637 sees Leclerc (mediums) go second, but he is still 0.774s off Verstappen's best.

"Traction is very poor, especially at low speed," reports Ocon. "Disaster!"

Bottas goes seventh and Gasly eighth, while Zhou can only manage 16th.

Albon's first flying lap sees the youngster go 14th on the mediums.

Perez (hards) improves to third with a 30.677. The Mexican subsequently closes to within 0.167s of his teammate, while Sargeant - on softs - goes third with a 30.327.

Sainz and Tsunoda also make the switch to the red-banded rubber.

Alonso posts an exploratory 31.942 on the hards.

Quickest in the two final sectors, Sainz goes quickest with a 29.357, but only 0.506s up on Verstappen's hard pace.

Tsunoda improves to fourth, as Leclerc heads out on the red-banded rubber.

"Bit of vibration under my brake pedal," reports Russell.

Piastri goes eleventh (30.902) on the mediums.

"Bouncing is pretty bad, mate," reports Hamilton.

Leclerc goes second with a 29.418, 0.061s off his teammate's pace.

In the Alpine garage, the rear of Ocon's car is getting plenty of attention from the mechanics.

"Are you aborting or pushing," Sargeant is asked. "Aborting," the American replies. "Then you'll have lap less," he is informed.

Back on track, Ocon (softs) goes quickest in S1, as teammate Gasly goes third overall (29.828). Ocon subsequently crosses the line at 29.319 to go top.

De Vries goes fourth with a 29.691, as Russell continues to complain of a steering vibration issue.

Leclerc raises the bar with a 29.280.

With 15 minutes remaining, Perez switches to the softs. No purples in the first two sectors, merely PBs, the Mexican finally crossing the line at 29.333 to go third, 0.053s down on Leclerc.

At which point Verstappen heads out on the red-banded rubber.

A PB in S1 is followed by a purple in S2. At the line the Dutchman posts 28.836 as he goes quickest by 0.444s.

Elsewhere, Norris improves to sixth with a 29.441.

The Aston Martin pair both switch to the softs, they are currently 19th (Alonso) and 20th.

No sooner has Piastri gone 8th than he is demoted by Alonso (29.268) and then Albon (29.089). Stroll subsequently goes 9th with a 29.471, the Canadian having lost time behind Gasly in the final corner.

Perez improves to second with a 29048, 0.212s off his teammate's pace.

Verstappen consolidates his top spot with a 28.600.

Russell goes wide at Brooklands.

According to the AWS graphic, Albon is the quickest on the straights.

"Car is all over the pace, in (Turns) 6 and 7," reports Russell.

Speaking at the end of the session, despite the lowly position of his drivers, Mercedes Andrew Shovlin insists that there are no real concerns and as the only team not to use the softs the German outfit, which spent much of the session testing its new parts, has yet to show its true pace here.

Then session ends. Verstappen is quickest, ahead of Perez, Albon, Alonso, Leclerc, Ocon, Sainz, Norris, Stroll and Piastri.

de Vries is eleventh, ahead of Hamilton, Gasly, Russell, Bottas, Tsunoda, Sargeant, Zhou, Magnussen and Hulkenberg.

Check out our Friday gallery from Silverstone here.