1951 Speedway National League Division Three
The 1951 National League Division Three was the fifth and final season of British speedway's National League Division Three
The league remained with 10 teams but there were changes. Oxford Cheetahs, Leicester Hunters and Liverpool Chads had all moved up to Division Two whilst Tamworth Tammies dropped out.
Plymouth Devils dropped down from Division Two. The three new sides were Cardiff Dragons, Long Eaton Archers and Wolverhampton Wasps.
Poole Pirates won their first title. Alan Smith of Plymouth topped the averages.
National Trophy Stage Three
- For Stage Two - see Stage Two
- For Stage Three - see Stage Three
Third Division Qualifying First round
| Date | Team one | Score | Team two |
| 05/04 | Cardiff | 52-56 | Rayleigh |
| 05/04 | Plymouth | 54-54 | Exeter |
| 02/04 | Poole | 69-39 | Aldershot |
| 02/04 | Exeter | 77-30 | Plymouth |
| 31/03 | Aldershot | 66-40 | Poole |
| 31/03 | Rayleigh | 68-40 | Cardiff |
| 31/03 | Swindon | 71-37 | Long Eaton |
| 29/03 | Long Eaton | 49-58 | Swindon |
Third Division Qualifying semifinals
| Date | Team one | Score | Team two |
| 16/04 | Exeter | 73-35 | Rayleigh |
| 16/04 | Poole | 61-47 | Swindon |
| 07/04 | Swindon | 66-41 | Poole |
| 14/04 | Rayleigh | 56-52 | Exeter |
Qualifying final
First leg'''Second leg'''
Festival of Britain Trophy
Group A| Team | PL | W | D | L | Pts |
| Poole | 6 | 5 | 0 | 1 | 10 |
| Exeter | 6 | 3 | 0 | 3 | 6 |
| Aldershot | 6 | 2 | 0 | 4 | 4 |
| Plymouth | 6 | 2 | 0 | 4 | 4 |
Group B
| Team | PL | W | D | L | Pts |
| Rayleigh | 6 | 5 | 0 | 1 | 10 |
| Swindon | 6 | 3 | 1 | 2 | 7 |
| Cardiff | 6 | 2 | 1 | 3 | 5 |
| Long Eaton | 6 | 1 | 0 | 5 | 2 |
Final
| Team one | Team two | Score |
| Poole | Rayleigh | 70–50, 57–63 |
Riders' Championship
Ken Middleditch won the National League Division Three Rider's Championship. The final was held at Penarth Road Stadium in Cardiff on 23 October.| Pos. | Rider | Pts |
| 1 |  Riders & final averagesAldershot
|