The competitors started on the western perimeter road and headed north towards a right-hand turn, the infamously fast Woodcote Corner. From there the track continued along the northern edge of the perimeter to a sharp right turn onto the main runway at Copse Corner. The circuit continued along the main runway, known for the race as Segrave Straight, to the point at which the two largest runways intersected. Here, in an attempt to better emulate a true road circuit, the course designers narrowed the track width using hay bales, to funnel the cars into a 130° left hairpin bend onto the second runway. At the end of the second runway the cars rejoined the perimeter road, just before the old Becketts Corner, before continuing on along long stretch of straight road in front of the main aircraft hangar complex, known appropriately as Hangar Straight.
At the end of the straight at now Stowe Corner, competitors rejoined the main runway (this southern portion now named the Seaman Straight), heading directly back towards the central hairpin complex. Once again, at the intersection of the two runways the track was narrowed and took a left-hand hairpin onto the second runway, heading back out to the perimeter road. The perimeter road was rejoined at Club Corner. From this point the track once again headed north towards the finish line, passing through the flat-out Abbey Curve en route. The total track length was approximately 3.7 miles (5.9 km), substantially longer than the 2.9 miles (4.7 km) of Silverstone's classic layout, and longer even than the current 3.2 mile (5.1 km) circuit design. This was the only Grand Prix event ever held on this track layout, as from 1949 onward Silverstone circuits used only the perimeter roads. To commemorate the opening of this new circuit, all drivers completing either the Grand Prix or 500 cc race received the RAC Silverstone Plaque.
The entry list for the Grand Prix was a very mixed affair, with brand new, full works cars being entered from Maserati, Talbot-Lago and Ferrari, with the majority of the remaining field made up of privateer entrants, commonly running pre-war cars. The organisers were particularly pleased to have attracted entries from leading continental firm Maserati; two of their brand new 4CLT/48 Sanremo models were entered: a works car for Luigi Villoresi, and one by British privateer Reg Parnell. A third 4CLT/48 was later entered for a second factory driver, Alberto Ascari, and a fourth was entered as a reserve car in the hands of local driver Leslie Brooke. Four Talbot-Lago T26C cars were also entered, including one for pre-war star driver Louis Chiron, and a fifth was held in reserve, entered by Lord Selsdon. Scuderia Ferrari entered two of its Ferrari 125 cars, however, the team decided at the last minute to concentrate their efforts on mainland Europe and failed to arrive.
Of the older vehicles entered, two of the most notable were the Maserati 4CLs from the Scuderia Platé and White Mouse Stable teams. These cars were to be driven by Toulo de Graffenried and Prince Bira respectively, both previously winners of major races. The ERA marque was well represented among the local privateers, and was bolstered by a factory entry from the firm's progenitor Raymond Mays. Another significant ERA entry was that of David Hampshire who drove R1A, the first ERA car to be constructed, dating from 1934. Leslie Johnson, owner of ERA in 1948, entered and drove one of the firm's 1939 E-type models. Although Peter Walker was also entered in an E-type, the car was unavailable on race day so he reverted to his own B-type, R10B.
Notable by their absence were the Alfa Romeo works team, with their dominant 158 Alfetta cars, who decided not to attend. One Alfa oddity was on show, however, as ex-Colditz prisoner of war, and future developer of four-wheel-drive, Tony Rolt drove the 1935 Bimotore, albeit with only one of its two engines in operation.
Despite the prestigious occasion running two hours before the main Grand Prix event, the 500 cc race was actually the first ever competitive race on the Silverstone Circuit the start was something of a shambles. When British Racing Drivers' Club President Lord Howe dropped the starting flag only two of the 34 drivers were ready to begin. Eric Brandon an experienced 500 cc driver, and the first man to win a 500 cc race in Britain was not even seated in his car! He recovered from this early set-back to finish in fifth place. Moss had dominated the British 500 cc race season up to this point, but his car lost drive during the race and challenger Rhiando won. John Cooper was second, and the 58-year-old Baronet of Bodicote, Sir Francis Samuelson (also a Cooper MkII driver) took third.
The works Maseratis were delayed on their way to Silverstone, and in their absence qualifying was dominated by Monagasque driver Chiron, in his Ecurie France-run Talbot-Lago. He took pole position with a time of 2:56.0, a second clear of de Graffenried's Maserati in second place. Third was taken by a second Talbot-Lago of Philippe Etancelin a further second behind de Graffenried. Despite driving a car a decade older than those in front of him, Bob Gerard managed to put his ERA R14B into fourth position, only two-tenths of a second behind Etancelin. Having missed qualifying, the Maseratis of Villoresi and Ascari were forced to start at the back of the field, in 24th and 25th positions, respectively.
From the very start, the Maserati 4CLTs of Villoresi and Ascari began to move rapidly through the field; while local driver Parnell's month-old 4CLT lasted less than a lap before its fuel tank split, ending his race. Another early retiree was Italian privateer Gianfranco Comotti, whose Talbot's brakes failed on lap three. A far more dramatic exit from the race was made by ERA pilot Geoffrey Ansell, who rolled R9B on lap 23. Fortunately for Ansell, he was thrown from the car and emerged from the accident unscathed.
As more cars failed, and through their superior pace, the works Maseratis gradually moved into the lead. Villoresi and his protege Ascari swapped the lead many times during the course of the race, never being more than a few seconds apart, except during pit stops, and Villoresi posted the fastest lap of the race: 2:52.0. Eventually, after the 65 laps were complete, it was also Villoresi who finished first, 14 seconds ahead of his team mate and half a lap ahead of Bob Gerard in ERA R14B. The only other finisher on the same lap as the leaders, but only a few seconds from having been lapped, was the Talbot of Louis Rosier.
| Pos | No | Driver | Manufacturer | Laps | Time |
|---|---|---|---|---|---|
| 1 | 18 | Luigi Villoresi | Maserati | 65 | 3:18:03.0 |
| 2 | 11 | Alberto Ascari | Maserati | 65 | + 14.0s |
| 3 | 16 | Bob Gerard | ERA | 65 | + 2:03.0 |
| 4 | 3 | Louis Rosier | Talbot-Lago | 65 | + 4:35.6 |
| 5 | 19 | B. Bira | Maserati | 64 | + 1 lap |
| 6 | 25 | John Bolster Peter Bell | ERA | 63 | + 2 laps |
| 7 | 24 | Peter Fotheringham-Parker David Hampshire | ERA | 60 | + 5 laps |
| 8 | 27 | Roy Salvadori | Maserati | 60 | + 5 laps |
| 9 | 20 | Emmanuel de Graffenried | Maserati | 59 | + 6 laps |
| 10 | 30 | George Dixon | ERA | 58 | + 7 laps |
| 11 | 14 | Peter Walker | ERA | 53 | + 12 laps |
| 12 | 9 | Bob Ansell George Bainbridge | Maserati | 50 | + 15 laps |