| Catagories | Records | | Catagories | Records |
| Occupational Therapists | 37 | | Oils - Edible | 49 |
| Office & Shop Cleaning Services | 421 | | Optical Goods - Mnfrs | 303 |
| Office Equipment Mnfrs & Distributors | 107 | | Optical Goods - Retail | 162 |
| Office Equipment Servicing & Maintenance | 189 | | Optical Goods - Wholesale | 205 |
| Office Furniture & Equipment | 1430 | | Opticians - Dispensing | 1195 |
| Office Furniture & Equipment - Hire & Leasing | 29 | | Opticians - Ophthalmic (Optometrists) | 4582 |
| Office Planning & Design Services | 169 | | Organic Foods | 360 |
| Office Premises - Retail | 50 | | Organs & Accessories - Sales & Service | 98 |
| Office Refurbishment Services | 430 | | Ornamental Metalwork | 136 |
| Office Rental | 242 | | Orthopaedic Care Equipment | 72 |
| Office Services | 258 | | Osteopaths | 1788 |
| Office Stationery Supplies | 959 | | Outboard Motors - Sales & Service | 58 |
| Oil & Gas Exploration Supplies & Services | 449 | | Outdoor Clothing & Equipment | 285 |
| Oil & Gas Extraction | 86 | | Outdoor Pursuit Organisers & Equipment | 486 |
| Oil Companies | 217 | | Oven Mnfrs | 20 |
| Oil Fuel Distributors | 797 | | Overall Hire Service | 13 |
| Oil Recycling & Disposal Services | 44 | | Overseas Property Agents | 210 |
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