Company Index
- O M V Trading - London
- O'Neill and Co Ltd - Glasgow
- Oak Industrial Supplies - Sutton in Ashfield
- Oakcliffe Rotajet Ltd - Ossett
- Oakmere Technical Services Ltd - Chester
- Oakville Ltd - London
- OAMPS (UK) Ltd - Esher
- Oasis Environmental Ltd - Sale
- Ocean Corporate Hygiene - Sunbury on Thames
- Ocean Energy and Resource Ltd - Chepstow
- Ocean Kinetics Ltd - Shetland
- Ocean Technical Systems Ltd - Sutton
- Oceaneering International Services Ltd - Aberdeen
- Oceanfix International Ltd - Aberdeen
- Oceanscan Ltd - Aberdeen
- Ocidron - Oxted
- Octavius Hunt Ltd - Bristol
- Oel-Held Ltd - Denbigh
- Oemeta Ltd - Banbury
- Ogden Group Of Companies - Doncaster
- OIE Services Ltd - Aberdeen
- Oil & Gas Associates Ltd - Dunstable
- Oil Analysis Services - Sevenoaks
- Oil and Gas Project Consultants Ltd - Woking
- Oil Direct - Caerphilly
- Oil Direct - Dromore
- Oil Equip Procurement Serve Ltd - London
- Oil Heat Ltd - Cowbridge
- Oil Inventions Ltd - Walsall
- Oil Plus Ltd - Newbury
- Oil Pollution Environmental Control Ltd - Batley
- Oil Recruitment Ltd - Knutsford
- Oil Search Plc - Tonbridge
- Oil States Klaper Ltd - Bathgate
- Oil States MCS Ltd - Barrow in Furness
- Oil Technics Ltd - Inverbervie
- Oilband Ltd - Buxton
- OilExec.com - London
- Oilfield Bearing International Ltd - Aberdeen
- Oilfield Chemical Technology Ltd - Aberdeen
- Oilfield Production Support (North Sea) Ltd - Aberdeen
- Oilfield Solutions - Inverurie
- Oilfield Testing Services - Great Yarmouth
- Oilfield Tool Inspection Ltd - Banchory
- Oilstore Ltd - Southampton
- Old Hall Performance - Coventry
- Oleo Solutions Ltd - York
- Oliver Valves - Knutsford
- Omega Data Services Ltd - Aberdeen
- Omega Resources Ltd - Alloa
- Omega Wire Ltd - Brierley Hill
- Omex Agriculture Ltd - Lincoln
- Omni Flow Computers Ltd - Bracknell
- Omnichem Ltd - Leicester
- OMV (UK) Ltd - London
- One Brand Group - Tetbury
- One For Instrumentation Ltd - Congleton
- Online Consultants - Newcastle upon Tyne
- Online Lubricants Ltd - Barking
- Onshore Oil Field Services Ltd - Market Rasen
- Onyvax Ltd - London
- Onyx Scientific Ltd - Sunderland
- OPM Furniture Ltd - London
- Opti-Pharma UK - Pontefract
- Optima International Ltd - Doncaster
- Optima Solutions Ltd - Aberdeen
- Optimol Lubricants - Shotts
- Optimus (Aberdeen) Ltd - Aberdeen
- Orange Chemicals Ltd - Winchester
- Oriel Systems Ltd - Chippenham
- Orion Valves Ltd - Wimborne
- Orkney Harbour, Department of Harbours - Orkney
- Osmose Ltd (T/u Protim and Solignum Ltd) - Marlow
- Osprey Oil and Gas Ltd - London
- OSS Group - Mersey
- OTM Consulting Ltd - Guildford
- Otto Simon Ltd - Cheadle (Cheshire)
- Outreach Ltd - Falkirk
- Owens Corning Veil UK Ltd - Liversedge
- Oxford Chemicals - Hartlepool
- OXUS Group Ltd - Aberdeen
- Oxy-Wax Ltd - Billingham
