Ahead of this morning's opening session, the air temperature is 15 degrees C, whilst the track temperature is 17 degrees. Cool, but typical of the great British summer unfortunately.

Unlike Spielberg, which had been completely resurfaced and new kerbs added at every corner, the only changes here since last year is the artificial grass which has been added in Turns 9 (Copse), 15 (Stowe) and 18 (Club).

There are two DRS zones, the detection point of the first is 25m before T3 (Village), with the activation point 30m after T5. The second detection point is at T10 (Maggotts) with the activation point 55m after T14 (Chapel).

Tyres this weekend are hard, medium and soft, the three last seen at the Spanish Grand Prix.

Back on a normal circuit - as was Austria of course - the teams are running a variety of upgrades here, including Honda which relates to the intake system on the ICE and aimed at improving the combustion efficiency and power output.

Of course, the big news of the last seven days has been the situation at Mercedes, where Toto Wolff insists Lewis Hamilton and Nico Rosberg are on their final warning following last week's clash, their third in five races as the Austrian pointed out.

There are two reserve drivers on duty this morning, Esteban Ocon is driving Kevin Magnussen's Renault whilst Charles Leclerc takes over Esteban Gutierrez' Haas.

Also, having abandoned plans to run the Halo device in Austria last week, Ferrari will be giving it an airing in this session, this being the real thing as opposed to the mock-up demonstrated in pre-season testing.

The lights go green and Austria hero Wehrlein leads the way, followed by Masa, Ocon, Bottas, Palmer and Perez.

The Red Bull duo are the first to post timers, Ricciardo posting 1:37.297, then Verstappen stopping the clock at 36.973 before the Australian responds with a 36.256 moments later.

Among the last out is Vettel, complete with Halo, leaving the Mercedes boys as the only 'no show'.

As the Red Bull duo trade fastest laps, Vettel completes his Halo run before returning to the pits.

As Verstappen posts 35.195, Perez becomes the third driver to post a time, the Mexican crossing the line at 38.251.

Fifteen minutes in and the Silver Arrows duo heads out, as Bottas, Grosjean and Wehrlein post their first times of the weekend. Hamilton waves to the fans on his out lap.

Rosberg goes quickest with a 34.885 on his first flying lap, Hamilton posting 42.106. Next time around the German improves to 33.484 and his teammate 41.881 following a lock-up at T15.

Grosjean improves to second (35.058), but remains 1.574 off Rosberg's pace.

A nice, clean lap sees Hamilton take the top spot, the Briton eclipsing his teammate by 0.166s.

T3 (Village) is catching out a number of drivers, Leclerc being the latest.

Hamilton ups the ante, the Briton posting 32.827 to go 0.657s clear of Rosberg.

All the tops times so far set on the mediums, quickest hard runner is Ricciardo in eighth, 2.693s off the pace.

Now it's Rosberg's turn to go quickest, the German posting 32.645.

On the softs, Nasr posts 36.349 to go tenth, just behind Raikkonen.

Approaching the half-hour, all but Ericsson, Sainz and Vettel have posted times, though the latter two are currently on track.

Raikkonen improves to third with a 34.621, but remains 2.143s off the pace as Hamilton raises the bar with a 32.478.

Leclerc spins at T3, the corner clearly bothering the French youngster. Then again, didn't a legendary Canadian driver make a number of similar mistakes on his F1 debut... in a McLaren, at this circuit.

Vettel posts 35.312 to go 13th, despite a massive lock-up at T6.

Alonso goes fourth, and Button fifth, much to the delight of the partisan crowd.

Shortly after Alonso improves to third, leapfrogging Verstappen who is further demoted when Vettel posts 34.081 to go fourth.

Ahead of the forty minute mark, at which point a set of tyres have to be handed back, Ericsson is back on track and looking to post his first time of the day.

At the forty-minute mark, it's: Hamilton, Rosberg, Alonso, Vettel, Verstappen, Hulkenberg, Button, Ricciardo, Raikkonen and Sainz. The Mercedes duo are around 1.5s clear of the next driver (Alonso), with third to thirteenth covered by around a second.

As ever, there is a brief lull. For a change it is a very brief lull, Rosberg heading out on a brand new set of mediums.

As teammate Hamilton heads out, Rosberg goes quickest in the first two sectors, finally crossing the line at 31.687 despite a mistake at Copse.

Hamilton, also on a new set of mediums, responds with a 31.654, despite only being quickest in S1.

Worryingly, Ericsson and Nasr are chatting with the guys on the pit-wall, the Swede yet to post a time. Then again, with the Swiss team missing this week's test because there are no new parts to run, could money be behind the decision to limit running this morning.

Like his teammate, Hamilton also makes a mistake at Copse, and subsequently heads back to the pits.

Check out our Friday gallery, here.