| Company | Search On | Records | Category | Sub category |
| L G Hawkins & Co Ltd | L G Hawkins | 1 | Engineering Equipment | Adhesives |
| Lacey-Hulbert Co Ltd | LaceyHulbert | 21 | Engineering Equipment | Compressors |
| Lacre Ltd | Lacre | 5 | Vehicles | Sweepers |
| L.Adams Ltd | LAdams | 1 | Manufacturing | Components |
| L'Aeromaritime | LaeroMaritime | 1 | Air Transport | Airlines |
| Laing & Son Ltd. John | Laing | 1 | Airfields | Construction |
| Lake Aircraft | Lake | 7 | Aircraft Manufacturers | Non UK |
| Laker Airways | Laker | 3 | Air Transport | Airlines |
| Lamblin | Lamblin | 17 | Components | Radiators |
| Lamplough & Son Ltd | Lamplough | 16 | Aircraft Manufacturers | |
| Lamp Manufacturing Co Ltd. The | LampManufacturing | 1 | Manufacturing | Metal Spinners |
| Lancashire Aircraft Co Ltd | LancashireAircraft | 13 | Aircraft Manufacturers | |
| Lancefield Aircraft Components | Lancefield | 14 | Role Equipment | Cabin Seating |
| Lancegaye Safety Glass (1934) Ltd | Lancegaye | 1 | Materials | Transparencies |
| Lanes British Aeroplanes Ltd | LanesBritish | 2 | Aircraft Manufacturers | |
| Langham Thompson. J. | LanghamThompson | 3 | Components | Electrical |
| Langite. Cork Manufacturing Co Ltd | Langite | 32 | Materials | Cork |
| Langley Alloys Ltd | LangleyAlloys | 8 | Materials | Aluminium Bronzes |
| Lang Propeller Ltd | LangPropeller | 13 | Components | Propellers |
| Lansing Bagnall Ltd | LansingBagnall | 4 | Ground Equipment | Ground Handling |
| Laporte Chemicals Ltd | Laporte | 5 | Chemicals | HTP |
| Land, Air, Sea Instrument Co | Lasco | 1 | Avionics | Radio |
| Lasham Airfield | Lasham | 1 | Training | Glider |
| Lasso Products | Lasso | 4 | Materials | Tape |
| Latex Upholstery Ltd | LatexUpholstery | 13 | Role Equipment | Cabin Seating |
| Laurence Norris & Co | LaurenceNorris | 2 | Components | Bearings |
| J.H.Lavender & Co Ltd | Lavender | 1 | Manufacturing | Castings |
| Laycock Engineering Ltd | LaycockEng | 29 | Components | Gears |
| Laystall | Laystall | 3 | Components | Crankshafts |
| L B Parkes And Co | LBParkes | 6 | Finishes | Anodising |
| L.Cameron & Son | LCameron | 1 | Materials | Metals |
| L.D.Gibbs & Co Ltd | LDGibbs | 12 | Engineering Equipment | |
| Lea Bridge Rubber Works Ltd | LeaBridge | 44 | Materials | Rubber |
| Leach, Stuart & Co | LeachStuart | 1 | Engineering Equipment | Machine Tools |
| Lear Avia Inc | LearAvia | 6 | Components | Electrical |
| Lear Jet Corporation | LearJet | 9 | Aircraft Manufacturers | Non UK |
| Lear Avia Inc | LearSiegler | 4 | Ground Equipment | Air Conditioning |
| LEC Refrigeration Ltd | LEC | 7 | Components | Galley |
| Legh & Co Ltd. C.Noel | Leghs | 3 | Materials | Wood |
| Leicester Airport | Leicester | 5 | Airfields | |
| Pettit & Thompson Air Transport Ltd | Leisure | 6 | Leisure | Enthusiast Tours |
| Lennig Chemicals Ltd | LennigChemicals | 2 | Chemicals | Transparencies |
| Lentern (Aircraft) Ltd | Lentern | 9 | Aircraft Parts | AGS |
| Leo Ripault & Co | LeoRipault | 30 | Components | Spark Plugs |
| Leo Swain & Co Ltd | LeoSwain | 1 | Ground Equipment | Oil Reclamation |
| LEP Transport & Depository Ltd | LEP | 3 | Transport | Logistics |
| Le Prieur Instruments | LePrieur | 1 | Instrument Manufacturers | Navigation |
| Letov | Letov | 1 | Aircraft Manufacturers | Non UK |
| Lewin. T.M. | Lewin | 3 | Clothing | Uniforms |
| Lewis Spring Co Ltd. The | LewisSpring | 5 | Components | Springs |
| Lewis & Taylor Ltd | LewisTaylor | 4 | Components | Piping |
| Leytonstone Jig & Tool Co Ltd | Leytool | 99 | Engineering Equipment | Hand Tools |
| LFE International | LFE | 3 | Components | Avionics |
| L.G.Hawkins & Co Ltd | LGHawkins | 5 | Factory | Lighting |
| L.H.Newton & Co Ltd | LHNewton | 5 | Fasteners | AGS |
| Light Alloys Ltd | LightAlloys | 3 | Manufacturing | Castings |
| Light Metal Forgings Ltd | LightMetal | 1 | Fabrication | Forging |
| Light Production Co Ltd | LightProduction | 3 | Components | Piston Rings |
| Linatex. Wilkinson Rubber Linatex Ltd | Linatex | 75 | Materials | Rubber |
| Lincoln Electric Company Ltd | LincolnElectric | 6 | Ground Equipment | Ground Power Units |
| Link Aviation Devices Inc | Link | 18 | Training | Flight Simulation |
| Linread Ltd | Linread | 19 | Fasteners | AGS |
| Lisson Aircraft & Precision Engineering Co Ltd | Lisson | 2 | Engineering | Precision Engineering |
| Listers Of Bradford | Listers | 4 | Materials | Composites |
| Litco Flight Aids | Litco | 2 | Sales & Brokerage | Spares Stockists |
| Literature | Literature | 221 | Literature | Periodicals |
| Littlefuse Inc | LittleFuse | 5 | Components | Electrical |
| Litton Industries | Litton | 20 | Components | Electronics |
| Liverpool Airport | Liverpool | 8 | Airfields | Airport |
| Livingstone & Doughty Ltd | LivingstoneDoughty | 2 | Engineering Equipment | Marking Crayons |
| L.K. Regent Ltd (Air Div) | LKRegent | 1 | Aircraft Suppliers | Sales |
| Lockheed | Lockheed | 275 | Aircraft Manufacturers | Non UK |
| Lodge Plugs Ltd | Lodge | 298 | Components | Spark Plugs |
| Loening Aeronautical Engineering Corporation | Loening | 2 | Aircraft Manufacturers | Non UK |
| Londex Ltd | Londex | 3 | Airfields | Seaplanes |
| London Die Casting Foundry Ltd | London Die Casting | 3 | Manufacturing | Castings |
| London Aircraft Co | LondonAircraftCo | 3 | Manufacturing | Stampings |
| London Aluminium Co Ltd | LondonAluminium | 17 | Materials | Aluminium |
| London Aviation Co | LondonAviationCo | 4 | Aircraft Manufacturers | |
| London Die Casting Foundry Ltd | LondonDie | 8 | Fabrication | Die Casting |
| London Die Casting Foundry | LondonDieCasting | 1 | Manufacturing | Castings |
| London Electric Firm | LondonElectric | 4 | Airfields | Lighting |
| London Label Co Ltd | LondonLabel | 6 | Fabrication | Fairings |
| London Name Plate Mfg Co Ltd | LondonNamePlate | 3 | Air Transport | Navigators |
| The London Plywood & Timber Co | LondonPlywood | 5 | Materials | Wood |
| London & Provincial School Of Flying | LondonProvincialSchool | 17 | Training | Flying School |
| London Sheet Metal Working & Welding Co | LondonSheetMetal | 3 | Manufacturing | Sheet Metal Work |
| London Varnish & Enamel Company Ltd. The | LondonVarnish | 1 | Finishes | Paints |
| Long & Hambly Ltd | LongHambly | 4 | Manufacturing | Mouldings |
| Lorival Manufacturing Co | Lorival | 5 | Manufacturing | Mouldings |
| Lorraine | Lorraine | 6 | Engine Manufacturers | Non UK |
| Louis Bamberger & Sons | LouisBamberger | 10 | Materials | Wood |
| Low Moor Alloy Steelworks Ltd | LowMoor | 14 | Manufacturing | Forging |
| Low Temperature Carbonisation Ltd | LowTemperature | 1 | Chemicals | Coal Petrol |
| L.Robinson & Co (Jubilee Clips) | LRobinson | 93 | Aircraft Parts | Fasteners |
| L.Roney Ltd | LRoney | 3 | Factory | Logistics |
| London School Of Air Navigation Ltd | LSAN | 5 | Training | Correspondence Courses |
| L.Steiner | LSteiner | 1 | Engineering Equipment | Vulcaniser |
| Ling Temco Vought | LTV | 23 | Aircraft Manufacturers | Non UK |
| Lucas Ltd. Joseph | Lucas | 204 | Components | Electrical |
| Lucraft & Westcott Ltd | LucraftWestcott | 3 | Components | Propellers |
| Ludlow Brothers (1913) Ltd | LudlowBrothers | 1 | Aeronautical Engineers | Components |
| Lufthansa. Deutsche | Lufthansa | 1 | Air Transport | Airlines |
| Luke Turner & Co Ltd | LukeTurner | 2 | Materials | Rope |
| Lunken Company. The | Lunken | 1 | Components | Piping |
| Lupton And Place Ltd | LuptonAndPlace | 25 | Fabrication | Machining |
| Luton Aircraft Ltd | LutonAircraft | 14 | Aircraft Manufacturers | |
| Luxair | Luxair | 1 | Air Transport | Airlines |
| Lydd Airport | Lydd | 1 | Airfields | |
| Lyle And Scott Ltd | LyleAndScott | 11 | Clothing | Flying Clothing |
| Lympne Airport | Lympne | 2 | Airfields | Airfield Operators |
| Lyne Hancock Ltd. James | LyneHancock | 1 | Materials | Rubber |
| Lysaght Ltd. John | Lysaght | 23 | Structures | Hangars |
