(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 |
(29) | 48.4y | CBP | Derek Pugh | (South London Harriers) | 1 FINAL | Motspur Park | 3 June 1950 |
| 48.40 | | Nicholas Atwell | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 25 May 2014 |
(31) | 48.43 | | Nicholas Atwell | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 26 May 2013 |
(32) | 48.48 | | Peter Phillips | (Herne Hill Harriers) | 2 FINAL | Kingsmeadow Stadium | 25 May 2014 |
(33) | 48.49 | | Dedan Simmons | (Harrow AC) | 1 FINAL | Kingsmeadow Stadium | 16 May 2004 |
(34) | 48.5 | | John Gostelow | (Hercules Wimbledon AC) | 3 FINAL | Motspur Park | 15 May 1976 |
(35) | 48.51 | | Nicholas Atwell | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 14 May 2017 |
(36) | 48.57 | | Peter Phillips | (Herne Hill Harriers) | 1 FINAL | Kingsmeadow Stadium | 13 May 2012 |
(37) | 48.6y | | John Strachan | (Hercules AC) | 2 FINAL | Motspur Park | 28 May 1960 |
| 48.6 | | Bolaji Odunsi | (Croydon Harriers) | 1 FINAL | Tooting Bec | 16 May 1987 |
| 48.6 | | David McKenzie | (Shaftesbury Barnet Harriers) | 1 HEAT 2 | Croydon Arena | 14 May 1994 |
| 48.6 | | Darren Bernard | (Herne Hill Harriers) | 1 HEAT 1 | Croydon Arena | 14 May 1994 |
| 48.6 | | Esmond Ferns | (Hercules Wimbledon AC) | 4 FINAL | Wimbledon Park | 11 May 1997 |
| 48.6 | | Michael Parper | (Belgrave Harriers) | 1 FINAL | Kingsmeadow Stadium | 9 May 1998 |
| 48.6 | | Dedan Simmons | (Harrow AC) | 2 FINAL | Kingsmeadow Stadium | 11 May 2003 |
(44) | 48.7y | | Robin Woodland | (Hercules AC) | 1 FINAL | Motspur Park | 1 June 1957 |
| 48.7y | | G Leroy | (Belgrave Harriers) | 2 FINAL | Motspur Park | 3 June 1961 |
| 48.7 | | Danny Laing | (South London Harriers) | 1 FINAL | Motspur Park | 18 May 1974 |
| 48.7 | | Rod Milne | (Guildford & Godalming AC) | 1 FINAL | Motspur Park | 13 May 1978 |
(48) | 48.71 | | Ryan Thomas | (Belgrave Harriers) | 1 FINAL | Kingsmeadow Stadium | 11 May 2008 |
(49) | 48.77 | | Dedan Simmons | (Harrow AC) | 1 FINAL | Kingsmeadow Stadium | 15 May 2005 |
(50) | 48.78 | | Samuel Adeyemi | (Herne Hill Harriers) | 3 FINAL | Kingsmeadow Stadium | 15 May 2016 |
(51) | 48.8y | | Alan Sexton | (Belgrave Harriers) | 1 FINAL | Motspur Park | 30 May 1953 |
| 48.8y | | Raymond Eve | (Mitcham AC) | 1 FINAL | Motspur Park | 25 May 1963 |
| 48.8 | | Bolaji Odunsi | (Croydon Harriers) | 1 FINAL | Motspur Park | 19 May 1984 |
(54) | 48.82 | | Jamal Clarke | (Windsor, Slough, Eton & Hounslow AC) | 1 FINAL | Kingsmeadow Stadium | 12 May 2024 |
(55) | 48.86 | | Lawrence Croll-Mensah | (Herne Hill Harriers) | 2 FINAL | Kingsmeadow Stadium | 13 May 2012 |
(56) | 48.9y | | Ollie Baggott | (Surrey AC) | 2 FINAL | Motspur Park | 30 May 1964 |
| 48.9y | | Nick Lovatt | (Mitcham AC) | 1 FINAL | Motspur Park | 8 June 1968 |
| 48.9 | | Rod Milne | (Guildford & Godalming AC) | 1 HEAT 1 | Motspur Park | 10 May 1979 |
| 48.9 | | Paul Batten | (Essex Beagles) | 1 FINAL | Motspur Park | 21 May 1983 |
| 48.9 | | Paul Batten | | 2 FINAL | Motspur Park | 19 May 1984 |
| 48.9 | | David McKenzie | (Croydon Harriers) | 1 FINAL | Tooting Bec | 14 May 1988 |
| 48.9 | | Dan Donovan | (Crawley AC) | 1 FINAL | Croydon Arena | 17 May 1992 |
| 48.9 | | Peter Phillips | (Herne Hill Harriers) | 2 FINAL | Kingsmeadow Stadium | 24 May 2015 |
(64) | 48.94 | | Jamal Clarke | (Windsor, Slough, Eton & Hounslow AC) | 1 HEAT 2 | Kingsmeadow Stadium | 12 May 2024 |
(65) | 48.97 | | Joe Godsell | (Blackheath & Bromley Harriers AC) | 1 FINAL | Kingsmeadow Stadium | 14 May 2006 |
| 48.97 | | Samuel Adeyemi | (Herne Hill Harriers) | 2 FINAL | Kingsmeadow Stadium | 14 May 2017 |
(67) | 49.0y | | J Perris | (Battersea Grammar School) | 3 FINAL | Motspur Park | 3 June 1961 |
| 49.0 | | Danny Laing | (South London Harriers) | 2 FINAL | Motspur Park | 19 May 1973 |
| 49.0 | | Mark Clark | (Guildford & Godalming AC) | 1 FINAL | Motspur Park | 14 May 1977 |
| 49.0 | | Allan Cord | (Herne Hill Harriers) | 2 FINAL | Motspur Park | 17 May 1980 |
| 49.0 | | David Mote | (Surrey AC) | 3 FINAL | Motspur Park | 17 May 1980 |
| 49.0 | | Bolaji Odunsi | (Croydon Harriers) | 2 FINAL | Motspur Park | 21 May 1983 |
| 49.0 | | Sam Kabiswa | (Croydon Harriers) | 1 FINAL | Croydon Arena | 16 May 1993 |
| 49.0 | | Chris Harris | (Woking AC) | 1 FINAL | Croydon Arena | 12 May 1996 |
| 49.0 | | Michael Parper (U20) | (Belgrave Harriers) | 1 HEAT 1 | Wimbledon Park | 11 May 1997 |
| 49.0 | | Richard David | (Belgrave Harriers) | 2 FINAL | Kingsmeadow Stadium | 9 May 1998 |
| 49.0 | | Michael Parper | (Belgrave Harriers) | 2 FINAL | Kingsmeadow Stadium | 12 May 2002 |
(78) | 49.07 | | Peter Phillips | (Herne Hill Harriers) | 3 FINAL | Kingsmeadow Stadium | 14 May 2017 |
(79) | 49.1y | | Alan Sexton | (Belgrave Harriers) | 1 FINAL | Motspur Park | 22 May 1954 |
| 49.1y | | Terry Higgins | (Herne Hill Harriers) | 1 FINAL | Motspur Park | 4 June 1955 |
| 49.1y | | Robin Woodland | (Hercules AC) | 1 FINAL | Motspur Park | 31 May 1958 |
| 49.1y | | Clive Ryan | (Belgrave Harriers) | 2 FINAL | Motspur Park | 30 May 1959 |
| 49.1 | | Mark Clark | (Guildford & Godalming AC) | 2 FINAL | Motspur Park | 12 May 1979 |
(84) | 49.13 | | Jamal Clarke | (Windsor, Slough, Eton & Hounslow AC) | 1 FINAL | Kingsmeadow Stadium | 1 August 2021 |
(85) | 49.14 | | Tim Kuria | (Woking AC) | 2 FINAL | Kingsmeadow Stadium | 26 May 2013 |
| 49.14 | | Nicholas Atwell | (Herne Hill Harriers) | 1 HEAT 1 | Kingsmeadow Stadium | 14 May 2017 |
(87) | 49.2y | CBP | Derek Pugh | (South London Harriers) | 1 FINAL | Motspur Park | 7 June 1947 |
| 49.2y | | John Carter | | 2 FINAL | Motspur Park | 1 June 1957 |
| 49.2y | | Ian Morgan | (Guy's Hospital ) | 2 FINAL | Motspur Park | 8 June 1968 |
| 49.2 | | Stuart Paton | (Belgrave Harriers) | 2 HEAT 3 | Tooting Bec | 14 May 1988 |
| 49.2 | | P J Speed-Andrews | (Kingston AC & Polytechnic Harriers) | 2 FINAL | Croydon Arena | 16 May 1993 |
| 49.2 | | Jonathon Squirrell | (Belgrave Harriers) | 2 FINAL | Croydon Arena | 12 May 1996 |
(93) | 49.21 | | Frederick Afrifa | (Crawley AC) | 4 FINAL | Kingsmeadow Stadium | 14 May 2017 |
(94) | 49.22 | | Nicholas Atwell | (Herne Hill Harriers) | 1 HEAT 1 | Kingsmeadow Stadium | 26 May 2013 |
| 49.22 | | Jason Hoyle | (Thames Valley Harriers) | 1 FINAL | Kingsmeadow Stadium | 14 May 2023 |
(96) | 49.26 | | Samuel Adeyemi | (Herne Hill Harriers) | 3 FINAL | Kingsmeadow Stadium | 26 May 2013 |
(97) | 49.3y | | F S Whittingham | (Blackheath Harriers) | 1 FINAL | Alexandra Rec Ground, Surbiton | 1 June 1935 |
| 49.3y | | Terry Higgins | (Herne Hill Harriers) | 2 FINAL | Motspur Park | 22 May 1954 |
| 49.3y | | Mick Hill | (Mitcham AC) | 2 FINAL | Motspur Park | 21 May 1966 |
| 49.3 | | Michael Alleyne | (Belgrave Harriers) | 2 FINAL | Motspur Park | 18 May 1985 |
| 49.3 | | Bolaji Odunsi | (Croydon Harriers) | 1 FINAL | Motspur Park | 17 May 1986 |
| 49.3 | | Michael Alleyne | (Belgrave Harriers) | 2 FINAL | Motspur Park | 17 May 1986 |
| 49.3 | | D Hart | (Belgrave Harriers) | 1 FINAL | Croydon Arena | 19 May 1991 |
| 49.3 | | Jon Sanders | (Kingston AC & Polytechnic Harriers) | 2 FINAL | Croydon Arena | 17 May 1992 |
| 49.3 | | Chris Harris | (Woking AC) | 5 FINAL | Wimbledon Park | 11 May 1997 |
| 49.3 | | Nathan Honour | (Woking AC) | 1 FINAL | Kingsmeadow Stadium | 8 May 1999 |
|
106 performances of 49.30 or better. |