The three-time champion led from start to finish in his Motorbase Performance-run Ford Focus ST, and never came under serious threat.
Behind Sutton, reigning title holder Tom Ingram similarly held second position throughout in his Excelr8 Motorsport Hyundai i30 N.
Ingram regularly came under pressure from Thruxton king Josh Cook – the circuit’s all-time BTCC wins record holder had to shake off the fast-starting West Surrey Racing-run BMW 330e M Sport of Jake Hill over the opening corners, then set the fastest lap as his One Motorsport Honda Civic Type R closed the gap to Ingram.
Since he came into the weekend outside the top seven in the championship, Cook had the standard eight laps use of the hybrid power boost to the two of Ingram (and one of Sutton), but even this advantage was insufficient to overcome the Hyundai in front.
Ingram had saved his hybrid use for the final two laps, but the computer said no and he found himself locked out, yet still pulled away from Cook.
Ahead of this duo, Sutton held the gap at just under two seconds for the majority of the distance, before taking the chequered flag 2.513s in front of Ingram.
“I just had to maximise the beginning – we’ve been strong there the past few races,” said Sutton.
“Josh closing up to Tom kind of gave me the breathing space. Just looking after that tyre [the front-left in particular] is a challenge around there – they take a beating.
Hill had a lonely race to fourth, while Dan Cammish, from ninth on the grid, worked his Motorbase Ford past the WSR BMW of Colin Turkington for fifth on lap two.
Cammish and Turkington circulated in close proximity throughout, but the Berkshire-domiciled Yorkshireman held on.
Rory Butcher made good early progress from 10th on the grid in the lead Speedworks Motorsport Toyota Corolla and passed second-row qualifier Mikey Doble’s Power Maxed Racing Vauxhall Astra for seventh on lap five.
As Butcher pulled away, attention turned to the massive ruckus at the bottom end of the top 10.
Ricky Collard (Speedworks Toyota) briefly pierced the defences of Doble with a few laps remaining, but the rookie fought back at the chicane and Collard missed the turns completely.
But he then played ball and backed off, and once again it became a battle between Doble, Collard and Adam Morgan (WSR BMW).
Collard and Morgan then lost out on the final lap, and it was Aron Taylor-Smith who came through to complete a PMR Vauxhall 8-9, with Bobby Thompson 10th in his Team Hard Cupra Leon.
Dan Rowbottom had worked his Motorbase Ford past this group by half-distance, only to be forced to the pits with a puncture.
BTCC Thruxton Race 1 Results (16 laps):
| Cla | Driver | Time | Gap |
|---|---|---|---|
| 1 |  Ashley Sutton |
20'41.048 | |
| 2 | Tom Ingram |
20'43.561 | 2.513 |
| 3 | Josh Cook |
20'45.134 | 4.086 |
| 4 | Jake Hill |
20'49.554 | 8.506 |
| 5 | Dan Cammish |
20'51.801 | 10.753 |
| 6 | Colin Turkington |
20'52.176 | 11.128 |
| 7 | Rory Butcher |
21'02.989 | 21.941 |
| 8 | Mikey Doble | 21'08.019 | 26.971 |
| 9 |  Aron Taylor-Smith |
21'08.746 | 27.698 |
| 10 | Bobby Thompson | 21'09.012 | 27.964 |
| 11 | Ricky Collard |
21'09.313 | 28.265 |
| 12 | Tom Chilton |
21'11.147 | 30.099 |
| 13 | Adam Morgan |
21'11.243 | 30.195 |
| 14 | Aiden Moffat |
21'11.553 | 30.505 |
| 15 | Ronan Pearson | 21'12.611 | 31.563 |
| 16 | Dexter Patterson | 21'12.763 | 31.715 |
| 17 | George Gamble | 21'13.544 | 32.496 |
| 18 | Andrew Watson |
21'13.733 | 32.685 |
| 19 | Stephen Jelley |
21'22.694 | 41.646 |
| 20 | Will Powell | 21'24.909 | 43.861 |
| 21 | Sam Osborne |
21'25.617 | 44.569 |
| 22 | Nicolas Hamilton | 21'36.327 | 55.279 |
| 23 | Jade Edwards | 21'44.273 | 1'03.225 |
| 24 | Daniel Rowbottom |
21'58.217 | 1'17.169 |
| Daniel Lloyd |
21'38.539 | 3 Laps | |
| Nick Halstead | 20'47.167 | 5 Laps | |
| Jack Butel | 15'37.727 | 6 Laps | |
| View full results | |||
