These companies in the United Kingdom are primarily large engineering services firms, many with a long history. They offer a broad range of specialized services, from energy infrastructure to digital systems. Petrofac, for example, is an international energy service provider, while Atkins transforms global infrastructure and energy systems. Ricardo is a global consulting firm focusing on transport, energy, and climate, and PRIME GROUP is an IT consulting and engineering group. Altrad Babcock specializes in construction and aftermarket services for various sectors, and Marshall works on military aircraft maintenance and manufacturing.
The data shows a concentration of headquarters in London, indicating a central hub for these operations. Many of these companies were founded in the 20th century, with several established before World War II, such as Ricardo (1915), Marshall (1909), and ABL (1856), suggesting a mature and established engineering sector.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
Petrofacpetrofac.com
International energy service provider specializing in designing, building, managing, and maintaining oil, gas, refining, and renewable energy infrastructure for leading energy companies worldwide |
14,616 | |||
| 2 |
Atkinsatkinsrealis.com
World-class engineering services and nuclear organization connecting people, data, and technology to transform global infrastructure and energy systems through design and management. |
9,798 | |||
| 3 |
PRIME GROUPweareprimegroup.com
A leading international IT consulting and engineering group with 12 companies, 3100 professionals, and offices across Europe, focusing on consultancy, nearshore, and software development |
3,359 | |||
| 4 |
Ricardoricardo.com
Global consulting firm providing strategic, environmental, and engineering solutions focused on transport, energy, and climate for sustainability. |
2,888 | |||
| 5 |
Bilfinger UKbilfinger.com
A leading engineering and maintenance provider with 4,000 employees in the UK, part of Europe's largest industrial services group |
2,688 | |||
| 6 |
Cavendish Nuclearcavendishnuclear.com
A leading nuclear services provider with international presence, specializing in innovative solutions across the nuclear energy life cycle |
1,908 | |||
| 7 |
ABLabl-group.com
Global independent energy and marine consultant de-risking and driving energy transition, offering expertise in renewables, maritime, and oil and gas sectors worldwide |
1,687 | |||
| 8 |
Altrad Babcockaltradbabcock.com
Specialists in construction, aftermarket, and upgrade services for thermal power, nuclear, oil & gas, petrochemical, and process sectors worldwide |
1,546 | |||
| 9 |
Marshallmarshallgroup.com
Specializes in military aircraft maintenance, repair, overhaul, precision manufacturing, and bespoke mission conversions for global defense and aerospace clients. |
1,273 | |||
| 10 |
TWItwi-global.com
Global technology engineering leader offering research and consultancy services to members across various industries, specializing in structural integrity, materials testing, welding, and training |
930 | |||
| 11 |
Aureosaureos.com
Multi-disciplinary services, design, engineering, installation, maintenance, crisis response for essential infrastructure across power, renewables, nuclear, railways, highways, local governments. |
907 | |||
| 12 |
RED Engineering Designred-eng.com
Specialist building services and ICT engineers providing technical expertise to enable digital infrastructure and achieve zero carbon built environments globally. |
862 | |||
| 13 |
SES Engineering Servicesses-ltd.co.uk
A design-led M&E provider with a rich history of engineering excellence, focusing on innovative and digital solutions for complex projects |
723 | |||
| 14 |
Briggs Equipment UK Ltdbriggsequipment.co.uk
Unique engineering and equipment provider offering Hyster and Yale materials handling products, full servicing, finance, rental, and asset management support. |
700 | |||
| 15 |
Altrad Sparrowsaltradsparrows.com
Global provider of specialist equipment and engineering services to energy and industrial sectors Offers tailored solutions for lifting, handling, cable laying, and fluid power needs worldwide |
662 | |||
| 16 |
Aktrion Groupaktrion.com
The company provides fully managed quality support solutions for the automotive industry, including remarketing centers and optimizing product quality and efficiency |
601 | |||
| 17 |
Protec Fire and Security Groupprotec.co.uk
A leading life safety systems integrator with 55 years of experience, offering reliable products and services across diverse building sectors globally |
584 | |||
| 18 |
ALTEN LTD - UKalten.co.uk
Leading global engineering and IT consultancy, supporting clients' development strategies with focus on innovation, R&D in various sectors like aerospace, automotive, and IT. |
563 | |||
| 19 |
nexosnexos.solutions
A diverse workforce providing fully integrated services for Brownfield EPC scopes for offshore assets, focusing on efficiency and cost-effectiveness |
543 | |||
| 20 |
Genesisgenesisenergies.com
A market-leading advisory company specializing in providing technical and advisory services for the energy industry, focused on sustainability and innovation |
531 | |||
| 21 |
Quartzelec Limitedquartzelec.com
A leading independent electrical engineering group offering solutions and services for industrial, infrastructure, commercial sectors, with 100+ years of experience worldwide |
508 | |||
| 22 | 495 | ||||
| 23 |
Fichtner Consulting Engineers Ltdfichtner.co.uk
Independent engineering consultancy firm providing technical advisory and project management services in various sectors, with a focus on impartiality and client interests |
449 | |||
| 24 |
WGM Engineering Ltdwgmengineering.co.uk
A Glasgow-based family business offering safe and sustainable engineering solutions including mechanical, electrical, civil engineering, renewable energy, project management, and more |
440 | |||
| 25 |
TEAM, Inc. UK, Africa, Caspianteaminc.com
A leading industrial services company specializing in construction, maintenance, and monitoring of pressurized piping systems for various industries worldwide ISO9001 and ISO14001 accredited |
439 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 26 |
TR, part of the Trifast plc grouptrfastenings.com
An international specialist in industrial fastenings & components, providing design, engineering, manufacturing, & distribution services to global assembly industries worldwide |
424 | |||
| 27 |
Capulacapula.com
A leader in system integration for industrial environments, focusing on digital transformation and operational technology to optimize efficiency, performance, and safety |
412 | |||
| 28 | 379 | ||||
| 29 |
Retronix Semiconductorretronixsemiconductor.com
Global engineering service provider specializing in semiconductor and high-tech manufacturing industries Services include equipment relocation, tool refurbishment, project management, labor support, and surplus parts handling |
341 | |||
| 30 |
BMSIbmsi.co.uk
The company is the UK's leading independent systems integrator of Building Energy Management Systems, helping businesses reduce energy costs and achieve environmental goals |
338 | |||
| 31 |
Rainham Industrial Services Ltdrainhamis.com
Specialist industrial services company in the UK, offering installation, maintenance, refurbishment, and decommissioning for various sectors with a focus on innovative solutions |
325 | |||
| 32 | 321 | ||||
| 33 |
TEXOtexo.co.uk
Dynamic UK-based industrial services provider offering engineering, construction, surveying, design, recruitment, and more to support onshore and offshore projects with a strong focus on people development |
309 | |||
| 34 |
MacTaggart Scottmactag.com
Scottish engineering company founded in 1898 specializing in providing equipment for Naval Defence and Marine industry, including lifts, handling systems, and propulsion units |
267 | |||
| 35 |
NIS Ltdnisltd.com
An engineering organization providing bespoke design and manufacturing services to quality-driven clients, aiming to deliver excellence while delighting customers |
233 | |||
| 36 |
Actemium UKactemium.co.uk
Delivers bespoke electrical, automation, and mechanical engineering solutions across various industries, critical infrastructure, and manufacturing, supporting operational efficiency and resilience. |
229 | |||
| 37 |
Cambridge Design Partnershipcambridge-design.com
Innovative end-to-end partner for global brands and start-ups, creating breakthrough products and services through interdisciplinary collaboration and employee ownership |
204 | |||
| 38 |
Longitude Engineeringlongitude-engineering.com
Specialist design and engineering services for marine, energy, and defence markets globally, with a client-focused approach and agile responsiveness |
190 | |||
| 39 |
Heyne Tillett Steelhts.uk.com
Employee-owned engineering firm specializing in structural and civil projects, known for innovative design solutions, rigorous quality assurance, and collaboration with top industry professionals |
175 | |||
| 40 |
Apolloapollo.engineer
A prominent consultancy specializing in engineering and advisory services for hydrogen, carbon capture, renewables, nuclear, and oil and gas industries Multiple office locations |
167 | |||
| 41 |
Parker Technical Services - PAGE CLOSEDmarch-engineering.com
Parker Technical Services offers tailored technical solutions for the built environment, specializing in project management, energy solutions, and facilities services |
160 | |||
| 42 |
Drive System Designdrivesystemdesign.com
Specializing in rapid engineering and development of sustainable electrified propulsion systems, offering expertise in systems integration, simulation design, and development testing |
160 | |||
| 43 |
Maritime Developments Limitedmaritimedevelopments.com
Specializing in engineering solutions for global offshore industries, we offer bespoke lifting equipment, project engineering support, modular flex-lay equipment, and expert offshore personnel for successful project execution |
156 | |||
| 44 |
24-7 Group24-7group.co.uk
Integrated facilities management, engineering, and technical services delivering M&E projects, steelwork, fit-out, renewables, cabling, and fire systems nationwide. |
155 | |||
| 45 |
ACE Winches an Ashtead Technology companyashtead-technology.com
Global leader in lifting, pulling, and deploying solutions across energy and civils sectors, offering bespoke equipment packages and unrivaled technical expertise |
155 | |||
| 46 |
Consult Redconsult.red
A technology consulting firm specializing in intelligent device and system development, offering expertise in product design, hardware, embedded, and cloud technology |
152 | |||
| 47 |
UnitBirwelcounitbirwelco.com
Design, manufacture, and maintenance of thermal equipment including flare systems, fired heaters, and heat exchangers for oil, gas, power, and pharmaceutical industries. |
149 | |||
| 48 |
Hyde Group Limitedhydegroup.com
A UK-based engineering company with expertise in designing and manufacturing tooling solutions for commercial, defense, and nuclear industries, offering complete engineering services |
117 | |||
| 49 |
Orano Limitedorano.group
A global company specializing in transforming nuclear materials to support energy development, offering services throughout the fuel cycle with a focus on safety and innovation |
116 | |||
| 50 |
Nova Systems Internationalnovasystems.com
Global engineering services and technology solutions company, specializing in keeping nations and people safe through defense, essential services, and cybersecurity partnerships worldwide |
105 | |||
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How this list is built
Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 11, 2026.
More company lists in the United Kingdom
- The largest companies in the United Kingdom 36,548
- Multinational companies in the United Kingdom 7,458
- Financial services firms in the United Kingdom 3,711
- Financial Services companies in the United Kingdom 3,696
- Retail chains in the United Kingdom 3,289
- Professional services firms in the United Kingdom 2,706
- Software Development companies in the United Kingdom 2,600
- Manufacturers in the United Kingdom 2,159
- Companies with in-house R&D in the United Kingdom 1,930
- IT Services and IT Consulting companies in the United Kingdom 1,722
- Retail companies in the United Kingdom 1,596
- IT services companies in the United Kingdom 1,583
- Hotel and hospitality groups in the United Kingdom 1,461
- Companies with a mobile app in the United Kingdom 1,411
- Consulting firms in the United Kingdom 1,298
- E-commerce companies in the United Kingdom 1,246
- Hardware manufacturers in the United Kingdom 1,239
- Family-owned companies in the United Kingdom 1,224
- Hospitality companies in the United Kingdom 1,204
- Critical infrastructure operators in the United Kingdom 1,195
- Wellness and Fitness Services companies in the United Kingdom 1,151
- Retail Apparel and Fashion companies in the United Kingdom 1,085
- Subscription businesses in the United Kingdom 1,077
- Distributors and wholesalers in the United Kingdom 1,060