United Kingdom
| Engine name | Engine maker | Place | Active
years |
Notes |
|---|---|---|---|---|
| A.B.C. | All British Engine Company | 1909 - 1920 | ||
| A.B.C. Motors 1920 Ltd. | Brookland, Surrey | 1920 - 1923 | ||
| A.B.C. Motors Ltd. | 1923 - 1971 | |||
| Abtus | Abtus Ltd. | London | ||
| Advance | Advance Motor Manufacturing Lt d. | Northampton | 1903 - | |
| A.G.E.
British Bull |
Agricultural & General Enginerring | |||
| Ailsa Craig | Ailsa Craig | Chiswick, London | 1891 - | |
| The Albert Gas Engine | William Buttersworth | Albert Works, Manchester | 1890 - 1894 | |
| Alden | Alden Engine Company | Oxford | 1920 - | |
| Allan Brothers | Ashgrove Engineering Works | Aberdeen | 1898 - 1955 | Taken over by Wilson & Co |
| W H Allen | W. H. Allen Sons & Company Limited
Queens Engineering Works |
Bedford | ||
| Auto Diesel | Auto Diesel | Uxbridge, Middlesex | 1936 - 1970 |