(1) | 47.2 | CBP | Rod Milne | (Thames Valley Harriers) | 1 FINAL | Motspur Park | 17 May 1980 |
| 47.2 | CBP= | David McKenzie | (Shaftesbury Barnet Harriers) | 1 FINAL | Croydon Arena | 14 May 1994 |
| 47.2 | CBP= | Michael Parper (U20) | (Belgrave Harriers) | 1 FINAL | Wimbledon Park | 11 May 1997 |
(4) | 47.4 | | Donovan Reid | (Shaftesbury Barnet Harriers) | 1 FINAL | Tooting Bec | 20 May 1989 |
(5) | 47.75 | | Nicholas Atwell | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 15 May 2016 |
(6) | 47.77 | | Jamal-Marcus Rhoden-Stevens | (Shaftesbury Barnet Harriers) | 2 FINAL | Kingsmeadow Stadium | 15 May 2016 |
(7) | 47.8y | CBP | Martin Winbolt-Lewis | (London AC) | 1 FINAL | Motspur Park | 21 May 1966 |
| 47.8 | | Dapo Laifa | (Croydon Harriers) | 1 FINAL | Motspur Park | 18 May 1985 |
| 47.8 | | Dan Donovan | (Team Solent) | 2 FINAL | Wimbledon Park | 11 May 1997 |
| 47.8 | | Michael Parper | (Belgrave Harriers) | 1 FINAL | Croydon Arena | 13 May 2000 |
(11) | 47.9y | CBP | Bob Setti | (Herne Hill Harriers) | 1 FINAL | Motspur Park | 30 May 1964 |
| 47.9 | | Dan Donovan | (Team Solent) | 1 HEAT 2 | Wimbledon Park | 11 May 1997 |
| 47.9 | | Michael Parper | (Belgrave Harriers) | 1 FINAL | Kingsmeadow Stadium | 11 May 2003 |
(14) | 48.0 | | Darren Bernard | (Herne Hill Harriers) | 2 FINAL | Croydon Arena | 14 May 1994 |
(15) | 48.1y | CBP | Robin Woodland | (Hercules AC) | 1 FINAL | Motspur Park | 30 May 1959 |
| 48.1y | CBP= | Robin Woodland | (Hercules AC) | 1 FINAL | Motspur Park | 28 May 1960 |
(17) | 48.2y | | Bob Setti | (Herne Hill Harriers) | 1 FINAL | Motspur Park | 3 June 1961 |
| 48.2 | | Martin Winbolt-Lewis | (Achilles Club) | 1 FINAL | Motspur Park | 30 May 1970 |
| 48.2 | | Rod Milne | (Epsom & Ewell Harriers) | 1 FINAL | Motspur Park | 15 May 1982 |
| 48.2 | | Jon Sanders | (Kingston AC & Polytechnic Harriers) | 3 FINAL | Croydon Arena | 14 May 1994 |
| 48.2 | | Louis Burgess | (Epsom & Ewell Harriers) | 1 FINAL | Kingsmeadow Stadium | 12 May 2002 |
(22) | 48.3 | | Richard Demming | (Polytechnic Harriers) | 1 FINAL | Motspur Park | 19 May 1973 |
| 48.3 | | Mark Clark | (Guildford & Godalming AC) | 1 FINAL | Motspur Park | 15 May 1976 |
| 48.3 | | Bob Benn | (Croydon Harriers) | 2 FINAL | Motspur Park | 15 May 1976 |
| 48.3 | | Rod Milne | (Guildford & Godalming AC) | 1 FINAL | Motspur Park | 12 May 1979 |
| 48.3 | | James Hilston (U20) | (Belgrave Harriers) | 3 FINAL | Wimbledon Park | 11 May 1997 |
| 48.3 | | Dedan Simmons | (Harrow AC) | 1 HEAT 2 | Kingsmeadow Stadium | 11 May 2003 |
| 48.3 | | Nicholas Atwell | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 24 May 2015 |
|
28 performances of 48.30 or better. |