 | | | | Av Time | | | Place | Races | 1st | 2nd | 3rd | Trophies | |
Oaten J E | 37.9 | | | 152 | 1 | 0 | 0 | 0 | | |
| 1987 | | 37:52:19 | | Edwards S N & Oaten J E | Viking | 152 | | | | | |  |
Oates A J | 43.6 | | | 97 | 2 | 0 | 0 | 0 | | |
| 1983 | | 50:40:06 | | Oates A J & James D | 10th Wakefield Scouts | 73 | | | | | |  |
| 1986 | | 36:33:10 | | Delany D M & Oates A J | Pangbourne Advent. Dolphin | 120 | | | | | |  |
Oconnell Elly | 19.8 | | | 19 | 1 | 0 | 0 | 0 | | |
| 2023 | | 19:46:39 | | Oconnell Elly & Herwanger Jorg | Richmond | 19 | | | | | |  |
Offer T D | 23.4 | | | 62 | 1 | 0 | 0 | 0 | | |
| 1993 | | 23:21:58 | | Gerrard M F & Offer T D | Thames Valley Police | 62 | | | | | |  |
Offiler D | 29.4 | | | 15 | 1 | 0 | 0 | 0 | | |
| 1964 | | 29:21:25 | | Offiler D & Niven F | RAF Oakington | 15 | | | | | |  |
Ogbum W D | 31.1 | | | 73 | 2 | 0 | 0 | 0 | | |
| 1981 | | 34:45:56 | | Ogbum W D & Edyvean N J | Independent | 65 | | | | | |  |
| 1982 | | 27:25:59 | | Ogbum W D & Pocock DA | Independent | 80 | | | | | |  |
Ogeman Elin | 26.4 | | | 87 | 1 | 0 | 0 | 0 | | |
| 2014 | | 26:22:55 | | Lynch Maria & Ogeman Elin | Southampton | 87 | | | | | |  |
Okopski P | 36.3 | | | 123 | 1 | 0 | 0 | 0 | | |
| 1989 | | 36:20:05 | | Gilholm A J & Okopski P | HMS Osprey | 123 | | | | | |  |
Oldham Peter | 26.4 | | | 39 | 3 | 0 | 0 | 0 | | |
| 2002 | C2 | 30:05:24 | | Broad James & Oldham Peter | Independent | 71 | | | | | |  |
| 2003 | C2 | 25:58:12 | | Broad James & Oldham Peter | Independent | 21 | | | | | Canadian |  |
| 2004 | C2 | 23:16:07 | | Oldham Peter & Broad James | Independent | 25 | | | | | Canadian |  |
Olding T | 26.9 | | | 76 | 1 | 0 | 0 | 0 | | |
| 1982 | | 26:53:33 | | Scott P & Olding T | Exeter | 76 | | | | | |  |
Oliphant M R | 40.5 | | | 56 | 1 | 0 | 0 | 0 | | |
| 1967 | | 40:33:00 | | Oliphant M R & McKinley D B | Britannia College Dartmouth | 56 | | | | | |  |
Olive A | 22.8 | | | 18 | 1 | 0 | 0 | 0 | | |
| 1998 | | 22:47:00 | | Franks P & Olive A | University of Exeter | 18 | | | | | University |  |
Oliver G F | 28.2 | | | 26 | 1 | 0 | 0 | 0 | | |
| 1976 | | 28:12:55 | | Oliver G F & Self A J | 10 Para | 26 | | | | | Home Built |  |
Oliver Geoff | 28.0 | | | 81 | 1 | 0 | 0 | 0 | | |
| 2012 | C2 | 27:58:46 | | Oliver Geoff & Howard Jim | Sutton Bingham And District | 81 | | | | | |  |
Oliver George | 20.5 | | | 22 | 4 | 0 | 0 | 0 | | |
| 1982 | | 19:48:16 | | Oliver George & Nadal Kathleen | Nottingham | 17 | | | | | Mixed,Home Built |  |
| 1986 | | 19:56:55 | | Enoch Dave & Oliver George | Nottingham | 13 | | | | | |  |
| 1987 | C2 | 21:42:36 | | Oliver George & Young K W | Nottingham | 43 | | | | | Canadian |  |
| 1990 | | 20:35:12 | | Oliver George & Enoch Dave | Nottingham | 16 | | | | | |  |
Oliver Jonathan | 25.1 | | | 66 | 2 | 0 | 0 | 0 | | |
| 2015 | | 24:48:33 | | Newman Alex & Oliver Jonathan | Acu - Southampton Otc | 65 | | | | | |  |
| 2017 | | 25:30:32 | | Oliver Jonathan & Lea Edward | Independent | 66 | | | | | |  |
Oliver K | 23.6 | | | 53 | 1 | 0 | 0 | 0 | | |
| 1990 | | 23:37:16 | | Oliver K & Essex R W | Warren | 53 | | | | | |  |
Oliver K J | 35.0 | | | 68 | 1 | 0 | 0 | 0 | | |
| 1981 | | 34:58:13 | | Oliver K J & Pickering J | Mullard's and Old Edwardians R.C. | 68 | | | | | |  |
Oliver L | 22.6 | | | 13 | 1 | 0 | 0 | 0 | | |
| 1983 | | 22:39:47 | | Catchlove R A F & Oliver L | Gillingham | 13 | | | | | |  |
Oliver P A | 20.3 | | | 17 | 5 | 0 | 0 | 0 | | |
| 1978 | | 20:06:21 | | Oliver P A & Hemsell R E | Royal Engineers | 10 | | | | | |  |
| 1979 | | 19:40:23 | | Collins K & Oliver P A | Royal Engineers | 14 | | | | | |  |
| 1981 | | 20:12:11 | | Oliver P A & Jardine G | Royal Engineers | 8 | | | | | |  |
| 1982 | | 20:47:40 | | Oliver P A & Perfect R W J | Royal Engineers | 29 | | | | | |  |
| 1985 | | 20:47:53 | | Oliver P A & Egglestone G R | Royal Engineers | 22 | | | | | |  |
Oliver P G | 37.3 | | | 133 | 1 | 0 | 0 | 0 | | |
| 1988 | | 37:16:15 | | Oliver P G & Murray P L | Independent | 133 | | | | | |  |
Oliver R | 29.8 | | | 18 | 1 | 0 | 0 | 0 | | |
| 1964 | | 29:46:11 | | Davis M & Oliver R | RMA Sandhurst | 18 | | | | | |  |
Oloenshaw D | 43.9 | | | 11 | 1 | 0 | 0 | 0 | | |
| 1959 | | 43:54:00 | | Blackford G & Oloenshaw D | Worcester | 11 | | | | | |  |
Olsen D J | 36.1 | | | 17 | 1 | 0 | 0 | 0 | | |
| 1960 | | 36:06:50 | | Olsen D J & Cox J | RAF Hullavington | 17 | | | | | |  |
Olsen R | 21.2 | | | 35 | 1 | 0 | 0 | 0 | | |
| 1987 | | 21:13:39 | | Richardson David & Olsen R | Gillingham | 35 | | | | | |  |
Olver M J | 35.1 | | | 34 | 1 | 0 | 0 | 0 | | |
| 1969 | | 35:05:44 | | Olver M J & Breach M C | RMA Sandhurst | 34 | | | | | |  |
Oooley M T | 24.3 | | | 62 | 1 | 0 | 0 | 0 | | |
| 1992 | | 24:17:05 | | MacLeod Morna Lelsey & Oooley M T | West Cumbria | 62 | | | | | |  |
Oram D A | 22.8 | | | 54 | 1 | 0 | 0 | 0 | | |
| 1988 | | 22:45:55 | | Tyler K F & Oram D A | 8th Regiment RCT | 54 | | | | | |  |
Orenstein Simon | 28.0 | | | 77 | 1 | 0 | 0 | 0 | | |
| 2011 | C2 | 28:02:38 | | Edwards Roger A & Orenstein Simon | Chelmsford | 77 | | | | | |  |
Orman P | 34.5 | | | 28 | 1 | 0 | 0 | 0 | | |
| 1963 | | 34:28:32 | | Helsby C & Orman P | RAF Compton Bassett | 28 | | | | | |  |
Orpe I C | 36.2 | | | 107 | 1 | 0 | 0 | 0 | | |
| 1993 | | 36:14:30 | | Wilson T W & Orpe I C | Independent | 107 | | | | | |  |
Orton P | 48.5 | | | 163 | 1 | 0 | 0 | 0 | | |
| 1987 | | 48:30:54 | | Duncan P A & Orton P | N. Staffs Poly | 163 | | | | | |  |
Osbome R C | 26.8 | | | 72 | 1 | 0 | 0 | 0 | | |
| 1994 | | 26:49:50 | | Wilcock J H J & Osbome R C | Royal Marines Reserve - London | 72 | | | | | |  |
Osborne J N | 22.8 | | | 28 | 1 | 0 | 0 | 0 | | |
| 1999 | | 22:48:19 | | Osborne J N & Stuart J | Independent | 28 | | | | | |  |
Osborne Jonathan | 21.4 | | | 18 | 1 | 0 | 0 | 0 | | |
| 2019 | | 21:21:51 | | Guest Simon & Osborne Jonathan | Devizes | 18 | | | | | |  |
Osborne N | 27.9 | | | 101 | 1 | 0 | 0 | 0 | | |
| 1984 | | 27:55:01 | | Osborne N & Aylward R G | Endeavour | 101 | | | | | |  |
Osborne P A | 26.3 | | | 86 | 1 | 0 | 0 | 0 | | |
| 1984 | | 26:17:50 | | Osborne P A & Wise K S | Independent | 86 | | | | | |  |
Oseland D M | 21.6 | | | 9 | 2 | 0 | 0 | 0 | | |
| 1976 | | 23:58:25 | | Oseland D M & Ryan P M | Royal Marines | 13 | | | | | |  |
| 1977 | | 19:20:58 | | Dickins R & Oseland D M | Royal Marines | 5 | | | | | |  |
Osmond N R | 20.3 | | | 19 | 2 | 0 | 0 | 0 | | |
| 1988 | | 20:00:00 | | Osmond N R & Balmer S | Royal Engineers | 17 | | | | | |  |
| 1989 | | 20:36:07 | | Davis-Shuck P & Osmond N R | Royal Engineers | 21 | | | | | |  |
Ottley W R | 31.1 | | | 101 | 1 | 0 | 0 | 0 | | |
| 1989 | | 31:06:43 | | Hunt G C & Ottley W R | Axe Vale | 101 | | | | | |  |
Otto H J | 24.5 | | | 44 | 3 | 0 | 0 | 0 | | |
| 1983 | | 27:50:05 | | Jork R & Otto H J | Alster - Hamburg | 43 | | | | | |  |
| 1984 | | 24:21:40 | | Jork R & Otto H J | Alster - Hamburg | 59 | | | | | |  |
| 1986 | | 21:19:30 | | Jork R & Otto H J | Afster Hamburg | 29 | | | | | |  |
Ottway Pat | 37.9 | | | 47 | 1 | 0 | 0 | 0 | | |
| 2003 | C2 | 37:53:30 | | Ottway Pat & Seager Chris | Independent | 47 | | | | | |  |