The third session of the BRDC British Formula 3 Championship‘s final pre-season test at Brands Hatch Indy was the slowest of the day so far, as 10-degree track temperatures and rain meant the drivers weren’t able to get near the 43-second mark we saw in Session 2.
Zak O’Sullivan picked up where he left off for Carlin early on, setting a 57.802s lap after topping the first and second test sessions (the first with an identical time to Ayrton Simmons).
Sebastian Alvarez, Oliver Bearman, Christian Mansell and Reece Ushijima filled the rest of the top five within a second of O’Sullivan in the first ten minutes, for Hitech GP, Fortec Motorsports, Carlin and Hitech respectively.
The first ten minutes saw limited running with a red flag thrown for Bryce Aron, who spun his Carlin at Clarke Curve, but the session resumed shortly afterwards.
The times tumbled as the cars got back out on track, with Alvarez setting a 55.670s lap immediately, ahead of the Carlin pair of O’Sullivan and Mansell.
The wet conditions did see bigger gaps between the front and back of the field early on, as drivers struggled for grip around the shorter Indy circuit.
No such problems for Bearman, though, who set a 54.365s lap which was quickly beaten by Alvarez again with a 53.920.
Bart Horsten beat Bearman’s time by 0.001s to go second, before Christian Mansell jumped six places to the top with 16 minutes remaining.
Frederick Lubin showed his hand in the Arden after both Red Arrows propped up the Session 2 standings, going top with a 53.233s at the halfway point.
He and Alvarez were half a second clear of the rest of the field with 15 minutes remaining before a flurry of activity saw the top nine separated by eight tenths.
Lubin’s Arden team-mate Alex Connor went 0.009s quicker than Alvarez, before being overtaken by Bearman and Horsten as the session ran into the final 11 minutes.
O’Sullivan moved back up to third with a 53.051s, immediately beaten by Connor by just under a tenth.
The Dubai-based British driver continued his charge by going top with a 52.821s lap, paving the way for Christian Mansell to go a tenth-and-a-half faster.
Alvarez set the fastest lap eight times over the course of the session, and remained top heading into the final five minutes.
Bearman went ahead of Mansell with four to go, with Alex Connor fourth and Alex Fores improving to fifth.
O’Sullivan went back into third, then slipping to fourth as his team-mate Mansell jumped three positions to go top with a 52.361s as the session drew to a close.
The Carlin man and Roberto Faria swapped places in the last minute, with Bryce Aron recovering from his early spin to go ninth.
The session ended with the top ten as follows: Mansell, Alvarez, Bearman, O’Sullivan, Faria, Lubin, Aron, Connor, Fores, Simmons.
2021 BRDC British Formula 3 Brands Hatch Indy Third Test Session Results:
| Pos | No. | Driver | Nat. | Team | Time | Gap |
| 1 | 21 | Christian Mansell | AUS | Carlin | 52.361 | |
| 2 | 12 | Sebastian Alvarez | MEX | Hitech GP | 52.436 | +0.075 |
| 3 | 87 | Oliver Bearman | GBR | Fortec Motorsports | 52.453 | +0.092 |
| 4 | 51 | Zak O’Sullivan | GBR | Carlin | 52.477 | +0.116 |
| 5 | 7 | Roberto Faria | BRA | Fortec Motorsports | 52.538 | +0.177 |
| 6 | 78 | Frederick Lubin | GBR | Arden Motorsport | 52.589 | +0.228 |
| 7 | 23 | Bryce Aron | USA | Carlin | 52.701 | +0.340 |
| 8 | 27 | Alex Connor | GBR | Arden Motorsport | 52.821 | +0.460 |
| 9 | 90 | Alex Fores | GBR | Chris Dittmann Racing | 52.883 | +0.522 |
| 10 | 18 | Ayrton Simmons | GBR | Chris Dittmann Racing | 52.963 | +0.602 |
| 11 | 50 | Bart Horsten | AUS | Hitech GP | 52.990 | +0.629 |
| 12 | 43 | Mikkel Grundtvig | DEN | Fortec Motorsport | 53.255 | +0.894 |
| 13 | 81 | Max Marzorati | GBR | Chris Dittmann Racing | 53.702 | +1.341 |
| 14 | 13 | Reece Ushijima | JPN | Hitech GP | 53.820 | +1.459 |
| 15 | 3 | Javier Sagrera | ESP | Elite Motorsport | 53.958 | +1.597 |
| 16 | 99 | Jose Garfias | MEX | Elite Motorsport | 53.988 | +1.627 |
| 17 | 34 | Tom Lebbon | GBR | Elite Motorsport | 54.487 | +2.126 |
| 18 | 10 | Reema Juffali | SAU | Douglas Motorsport | 54.571 | +2.210 |
| 19 | 55 | Dexter Patterson | GBR | Douglas Motorsport | 54.610 | +2.249 |
