| Type: | NC |
| Country: | UK |
| Grand Prix: | BRDC International Trophy |
| Official Name: | XVIII BRDC International Trophy |
| Location: | Silverstone Circuit, Northamptonshire |
| Date: | 14 May |
| Year: | 1966 |
| Course: | Permanent racing facility |
| Course Mi: | 2.927 |
| Course Km: | 4.711 |
| Distance Laps: | 35 |
| Distance Mi: | 102.528 |
| Distance Km: | 165.003 |
| Pole Driver: | Jack Brabham |
| Pole Country: | Australia |
| Pole Team: | Brabham-Repco |
| Pole Time: | 1:29.8 |
| Fast Driver: | Jack Brabham |
| Fast Team: | Brabham-Repco |
| Fast Time: | 1:29.8 |
| Fast Country: | Australia |
| First Driver: | Jack Brabham |
| First Country: | Australia |
| First Team: | Brabham-Repco |
| Second Driver: | John Surtees |
| Second Country: | UK |
| Second Team: | Ferrari |
| Third Driver: | Jo Bonnier |
| Third Country: | Sweden |
| Third Team: | Cooper-Maserati |
The 18th BRDC International Trophy was a motor race, run to Formula One rules, held on 14 May 1966 at the Silverstone Circuit, England. The race was run over 35 laps of the Silverstone Grand Prix circuit, and was won by Australian Jack Brabham in the Brabham-Repco BT19. With no Race of Champions in 1966, the International Trophy formed the first major race of the European season, being run just a week before the start of the FIA World Championship in Monaco. The 1966 season was significant, as changes to the F1 formula had allowed an increase in engine capacity from 1.5L to 3L. This then was the first opportunity for many teams to test their new cars against top-line opposition.
The "return to power" caused some manufacturers significant problems, as the supply of suitable large-capacity engines was restricted.[1] Only four teams managed to provide true 3-litre cars this early in the season. Regular front runners Ferrari and Lotus were both prepared with new vehicles, as was former World Champion Jack Brabham's eponymous team, fielding Australian Repco engines. The fourth team to have a 3L car was Cooper, however, their engine was far from new. The team's first monocoque chassis, the Cooper T81 was fitted with what was in essence Maserati's 1950s engine, which had seen success in the Maserati 250F, bored out to the new capacity limit.[2] BRM's new H16 engine was also slated to appear, but reliability problems resulted in Peter Arundell being forced to withdraw his Lotus-BRM prior to qualifying.
From the beginning of practice it became apparent that the race would be a straight fight between the Ferrari of John Surtees and Jack Brabham's Brabham. The pair qualified at the head of the field, with Brabham taking pole by only 0.2 of a second. The race went the same way, with Brabham being forced to equal his pole time in order to stay ahead of Surtees's hard-charging Ferrari. Despite qualifying an impressive third, Jochen Rindt's Cooper developed mechanical troubles and dropped him back to fifth by the end of the race. However, the surprise of the field was the sister Cooper of Jo Bonnier - run by Bonnier's Anglo-Suisse Racing Team and painted in Swiss racing red and white - who managed to climb from sixth to take the third place on the podium. It would prove to be Bonnier's last podium finish in a Formula One car, after a prolific career dating back a decade. Close behind Bonnier, Denny Hulme managed to bring an ageing Brabham home in fourth.
| Pos. | Driver[3] | Constructor | Time/Ret. | Grid | |
|---|---|---|---|---|---|
| 1 |  Jack Brabham | Brabham-Repco | 52:57.6 | 1 | |
| 2 | John Surtees | Ferrari | + 7.4 s | 2 | |
| 3 |  Jo Bonnier | Cooper-Maserati | 35 laps | 6 | |
| 4 |  Denny Hulme | Brabham-Climax | 35 laps | 5 | |
| 5 |  Jochen Rindt | Cooper-Maserati | 34 laps | 3 | |
| 6 | John Taylor | Brabham-BRM | 33 laps | 10 | |
| 7 | Bob Anderson | Brabham-Climax | 32 laps | 9 | |
| 8 | Paul Hawkins | Lotus-Climax | 31 laps | 13 | |
| 9 | Vic Wilson | BRM | 24 laps | 11 | |
| Ret |  Jo Siffert | Cooper-Maserati | ret | 14* | |
| Ret |  Richie Ginther | Cooper-Maserati | overheating | 8 | |
| Ret | Mike Spence | Lotus-BRM | engine | 4 | |
| DNS |  Guy Ligier | Cooper-Maserati | (12) |