| 2 EXCEL ENGINEERING LIMITED | Lasham | A rating |
| 2H Offshore Engineering Ltd | Woking | A rating |
| 3K's Engineering Company Limited | Llanelli | A rating |
| A FARLOW ENGINEERING LTD | COLERAINE | A rating |
| A Squared Engineering Ltd | Perth | A rating |
| A-squared Studio Engineers Ltd | London | A rating |
| A.V. ATKINSON (FOURWAYS) LTD. | Sandhurst | A rating |
| A&B Engineering (Electrical Service Division) Limited | Liverpool | A rating |
| A&B Engineering (Mechanical Service Division) Limited | Liverpool | A rating |
| A2 Engineering Ltd | Crawley | A rating |
| AARAA ENGINEERING LTD | London | A rating |
| Aarsleff Ground Engineering Ltd | Newark on Trent | A rating |
| ABBOTTSWAY ENGINEERING LTD | london | A rating |
| ABD Engineering & Development LTD | Essex | A rating |
| ABMI Engineering UK Ltd | London | A rating |
| Ace Engineering Solutions Ltd | London | A rating |
| ACE UK ENGINEERING CONSULTANTS LTD | Reading | A rating |
| Acoustic & Engineering Consultants Limited | Stockport | A rating |
| ACRON ENGINEERING SERVICES (UK) LTD | London | A rating |
| Aden Engineering & Consultancy Ltd | Birmingham | A rating |
| Adept Consulting Engineers | Leeds | A rating |
| ADI Facilities Engineering | Birmingham | A rating |
| ADMC ENGINEERING LTD | London | A rating |
| ADP Consulting & Engineering Ltd | London | A rating |
| Advance engineering uk ltd | kings lynn | A rating |
| Advanced Compressor Engineering Services Limited | Wallingford | A rating |
| Advanced Engineering Group Ltd | OMAGH | A rating |
| Advansys Engineering Services and Consultancy Limited | Camberley | A rating |
| AEGIS Engineering Systems (AES) Ltd | Derby | A rating |
| AEROSPACE ENGINEERING SOLUTIONS LTD | BRAINTREE | A rating |
| Affinity Fire Engineering (UK) Limited | London | A rating |
| AGEMA ENGINEERING LTD | COVENTRY | A rating |
| Agile Engineering Consultancy Ltd | Frognall | A rating |
| Aidan Strain Electrical Engineering Ltd (ASEE Ltd) | Mullaghbawn | A rating |
| AIM Engineering & Fabrication Group Ltd | Falkirk | A rating |
| AIM ENGINEERS LTD | Bristol | A rating |
| Airbus Belfast Limited | Belfast | A rating |
| Airbus Defence and Space Limited | Portsmouth | A rating |
| Airbus Helicopters UK Limited | Kidlington | A rating |
| Airbus Operations Limited | Bristol | A rating |
| Airbus Protect Limited | Bristol | A rating |
| Aircraft Engineering Services Limited | Stansted | A rating |
| AJ Engineering & Construction Services Limited | Forres | A rating |
| AKN Engineering Limited | Bishop's Stortford | A rating |
| Alfred Cheyne Engineering Ltd | Turriff | A rating |
| All Pipe Engineering Limited | Northen Ireland | A rating |
| ALLIANCE DESIGN UK LTD T/A EDGE CONSULTING ENGINEERS | MANCHESTER | A rating |
| Allied Global Engineering Ltd | Glossop | A rating |
| ALMA ENGINEERING CO LTD | BEDFORSHIRE | A rating |
| Alpha Building Services Engineering Ltd | London | A rating |