Junction Name | Type | Location | Roads | Grid Reference | Notes |
Oakfield Corner | | Amersham, Buckinghamshire | - A416 Chesham Road
- B4441 Sycamore Road
- Hill Avenue
| 51°40′37″N 0°36′27″W / 51.67694°N 0.60750°W / 51.67694; -0.60750 | |
Oakgrove Roundabout | | Monkston, Milton Keynes | | 52°02′15″N 0°42′33″W / 52.03750°N 0.70917°W / 52.03750; -0.70917 | |
Oakhill Roundabout | | Oakhill, Milton Keynes | | 52°01′09″N 0°48′33″W / 52.01917°N 0.80917°W / 52.01917; -0.80917 | |
Ober Corner | | Ober Heath, New Forest | | 50°49′51″N 1°35′50″W / 50.83083°N 1.59722°W / 50.83083; -1.59722 | |
Ockham Junction | | Ockham, Surrey | - A3 Ripley By-pass
- B2215 Portsmouth road (formerly A3)
- B2039 Ockham Road
| 54°06′31″N 0°27′17″W / 54.10861°N 0.45472°W / 54.10861; -0.45472 | |
Octon Crossroads | | North Yorkshire | - B1249 Scarborough Road
- B1253 High Street
| 54°06′31″N 0°27′17″W / 54.10861°N 0.45472°W / 54.10861; -0.45472 | |
Odsal Top | | Bradford, West Yorkshire | | SE158306 | |
Offington Corner | Roundabout | Worthing, West Sussex | - A27 Crockhurst Hill
- A24 Findon Road
- A27/A24 Warren Road
- A2031 Offington Lane
- Goodwood Road
| TQ 13255 05598 | |
Offley Cross | Crossroads | Hitchin, Hertfordshire | - A505
- Carters Lane (aka Wibbly Wobbley Lane)
| 51°56′30″N 0°18′23″W / 51.94167°N 0.30639°W / 51.94167; -0.30639 | |
Old Craighall | | Musselburgh, Scotland | - A1
- A720 City of Edinburgh Bypass
- B6415 Old Craighall Road
| NT338707 | |
Old Cross | Crossroads | Hertford, Hertfordshire | - B158 Cowbridge
- B158 The Wash
- St Andrews Street
| TL325127 | |
Old Ford | Diamond Interchange | Old Ford, London | - A12 East Cross Route (formerly A102(M))
- B142 Wick Lane
| 51°32′02″N 0°01′20″W / 51.53389°N 0.02222°W / 51.53389; -0.02222 | Site of the historic ford along the Roman road from London to Essex (now mostly consisting of the A118 and then A12) |
Old Inns Interchange | | Cumbernauld, North Lanarkshire | | NS770766 | |
Old Malton Roundabout | | Malton, North Yorkshire | | SE801734 | |
The Old Pond | Roundabout | Cheshunt, Hertfordshire | - B176 Turner's Hill (formerly A10)
- B198 College Road (formerly A121)
| 51°42′07″N 0°02′05″W / 51.70194°N 0.03472°W / 51.70194; -0.03472 | |
Old Street Roundabout | | The City, London | | 51°31′34″N 0°05′16″W / 51.52611°N 0.08778°W / 51.52611; -0.08778 | |
Old Wolverton Roundabout | | Wolverton, Milton Keynes | | 52°03′42″N 0°49′46″W / 52.06167°N 0.82944°W / 52.06167; -0.82944 | |
The Oldbury Interchange | | West Midlands | | 52°29′33″N 2°01′07″W / 52.49250°N 2.01861°W / 52.49250; -2.01861 | The supermarket access road is off the adjacent island which passes under the M5. |
Ollerton Roundabout | | Ollerton, Nottinghamshire | - A614 Blyth Road
- A614 Old Rufford Road
- A616 Worksop Road
- A616 Ollerton Road
- A6075 Mansfield Road
- Newark Road
| 53°12′04″N 1°01′38″W / 53.20111°N 1.02722°W / 53.20111; -1.02722 | |
The Organ Crossroads | | Ewell, Surrey | - A24 Ewell Bypass
- A240 London Road
- B2200 London Road
| 51°21′15″N 0°14′46″W / 51.35417°N 0.24611°W / 51.35417; -0.24611 | |
Orrell Interchange | | Orrell, Wigan | | 53°32′03″N 2°41′54″W / 53.53417°N 2.69833°W / 53.53417; -2.69833 | |
Orsett Cock | Roundabout Interchange | Orsett, Thurrock (formerly in Essex) | - A13
- A128 Brentwood Road
- A1013 Stanford Road (former A13)
- Brentwood Road (southern end, former A128)
| TQ654812 | Named after the pub at the site of the former crossroads. |
Ossie Garvin Roundabout | Roundabout Interchange | Hayes, LB Hillingdon | | 51°30′58″N 0°24′05″W / 51.51611°N 0.40139°W / 51.51611; -0.40139 | Named after a local councillor who originally proposed the Hayes By-Pass, and died shortly before it was completed in 1992. |
Ottershaw Roundabout | | Ottershaw, Surrey | - A319 Chobham Road
- A320 Guildford Road
- B3121 Murray Road
| TQ022639 | |
The Oval, Kennington | | Kennington, London | - A3 Kennington Park Road
- A202 Camberwell New Road
- A23 Brixton Road
| TQ312776 | |
Oxley Park Roundabout | | Westcroft, Milton Keynes | | 52°00′38″N 0°47′54″W / 52.01056°N 0.79833°W / 52.01056; -0.79833 | |
Oxford Circus | | London | | 51°30′55″N 0°08′31″W / 51.51528°N 0.14194°W / 51.51528; -0.14194 | |