In the 1948 Isle of Man Tourist Trophy festival Harold Daniell, lap record holder since 1938, failed to finish the 1948 Senior TT on his Norton, and victory went to Norton team member, Artie Bell, "the flying Ulsterman". Norton dominated, taking the first three places, losing fourth to Geoff Murdoch's AJS, and then filling the next four places. There were thirty three Nortons in a field of fifty six.
Artie Bell also came third in the Junior TT with Freddie Frith taking the flag for first place, and A. R. (Bob) Foster coming second, both on Velocettes. Maurice Cann won the Lightweight with his DOHC 250 cc Moto Guzzi, followed by Roland Pike on a Rudge.
Three Clubman races were again included, for the second year, in the festival with the Clubman Senior race allowing entries of motorcycles up to 1,000 cc engine capacity.
Later in 1948, at the FICM (later called FIM) meeting in London, it was decided there would be a motorcycle World Championship along Grand Prix lines. It would be a six-race annual series with points for a placing, and a point for the fastest lap of each race. There would be four classes: 500cc, 350cc, 250cc and 125cc. In the past a Grand Prix had been an individual race. In 1949 for the first time, starting with the Isle of Man TT, a series of Grand Prix races would decide who would be the 1949 World Champion.
The 1948 TT also saw the first presentation of the Jimmy Simpson Trophy, awarded to the rider who completed the fastest lap of the meeting.[1]
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 |  Freddie Frith | Velocette | 81.59 mph | 3:14.33.6 | |
| 2 | Bob Foster | Velocette | 79.55 mph | 3:19.12.6 | |
| 3 | Artie Bell | Norton | 78.97 mph | 3:20.50.6 | |
| 4 | Johnny Lockett | Norton | 78.80 mph | 3:21.06.8 | |
| 5 | Maurice Cann | AJS | 77.27 mph | 3:25.06.6 | |
| 6 | Eric Briggs | Norton | 77.13 mph | 3:25.27.6 | |
| 7 | Leslie Graham | AJS | 76.97 mph | 3:25.54.2 | |
| 8 | Eric Oliver | Velocette | 76.94 mph | 3:25.58.8 | |
| 9 | S M Miller | Norton | 76.11 mph | 3:28.12.0 | |
| 10 | Tommy McEwan | AJS | 76.06 mph | 3:28.20.4 |
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 | Maurice Cann | Moto Guzzi | 75.12 mph | 3:30:49.0 | |
| 2 | Roland Pike | Rudge | 71.85 mph | 3:40.33.2 | |
| 3 | Doug St.J Beasley | Excelsior | 67.68 mph | 3:54.09.0 | |
| 4 | Ben Drinkwater | Moto Guzzi | 66.6 mph | 3:57.56.2 | |
| 5 | Ray Petty | New Imperial | 66.26 mph | 3:59.11.0 | |
| 6 | Jock McCredie | Excelsior | 64.98 mph | 4:03:52.2 |
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 | Jack D Daniells | 998 Vincent HRD | 80.51 mph | 1.52.29.6 | |
| 2 | F Phil Heath | 998 Vincent HRD | 79.58 mph | 1:53.49.0 | |
| 3 | Cyril A Stevens | 490 Norton | 76.01 mph | 1:59.03.4 |
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 | Ronnie J Hazlehurst | Velocette | 70.33 mph | 2.08.47.2 | |
| 2 | G W Robinson | AJS | 70.02 mph | 2:09.21.6 | |
| 3 | Milton Sunderland | Norton | 69.58 mph | 2:10.13.4 |
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 | Monty Lockwood | Excelsior | 64.93 mph | 1.44.37.6 | |
| 2 | Bill G Dehany | Excelsior | 63.35 mph | 1:47.13.8 | |
| 3 | Ron Carvell | 62.53 mph | 1:48.38.0 |
| Rank | Rider | Team | Speed | Time | |
|---|---|---|---|---|---|
| 1 | Artie Bell | Norton | 84.969 mph | 3:06.31.0 | |
| 2 | Bill Doran | Norton | 80.338 mph | 3:17.16.0 | |
| 3 | Jock A Weddell | Norton | 79.564 mph | 3:19:11.2 | |
| 4 | Geoff G Murdoch | AJS | 78.513 mph | 3:21.51.2 | |
| 5 | Noel Pope | Norton | 78.039 mph | 3:23.04.8 | |
| 6 | C W (Bill) Petch | Norton | 77.806 mph | 3:23.41.2 | |
| 7 | Henry Pinnington | Norton | 77.343 mph | 3:24.54.6 | |
| 8 | Jack Brett | Norton | 77.307 mph | 3:24.59.8 | |
| 9 |  Omobono Tenni | Moto Guzzi | 76.857 mph | 3:26.12.2 | |
| 10 | Eric Oliver | Velocette | 76.648 mph | 3:26.45.4 |