This list comprises corporate groups and holding companies based in London. These firms represent a range of sectors, including technology, construction, and healthcare. Notably, RELX is a global provider of information-based analytics, Balfour Beatty plc is an infrastructure group, Smollan partners with brands and retailers, and Informa is an international business in events and digital services. Acacium Group provides healthcare delivery, and KELLER specializes in geotechnical contracting.
The companies on this list are predominantly large groups. Several, such as Balfour Beatty plc, founded in 1909, and Coats, established in 1755, have long histories, indicating a presence of established enterprises within London's corporate landscape.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 | 37,600 | ||||
| 2 |
Balfour Beatty plcbalfourbeatty.com
A global infrastructure group with 25,000 employees delivering innovative and efficient transportation, power, building, and utility systems for economic growth and community support |
25,000 | |||
| 3 |
Smollansmollan.com
Partners with brands and retailers, building solutions that drive growth and create opportunities at the point of purchase. |
13,502 | |||
| 4 |
Informainforma.com
Leading international business in events, digital services, and academic knowledge, connecting specialists worldwide to learn, know, and do more in their fields |
9,410 | |||
| 5 |
SThreesthree.com
Connecting skilled STEM professionals with organizations to drive innovation and solve complex challenges through specialist brands and tailored workforce solutions. |
7,927 | |||
| 6 |
Acacium Grouplinktr.ee
Global healthcare delivery partner with 40+ years experience offering workforce access, technology, and expertise to improve healthcare, social care, and life sciences worldwide |
5,961 | |||
| 7 |
KELLERkeller.com
A global geotechnical specialist contractor that solves construction challenges with local focus, expertise, and a track record of successful projects |
5,930 | |||
| 8 | 5,122 | ||||
| 9 |
Cygnetcygnetgroup.com
Providing health and social care services for individuals with mental health needs, brain injuries, eating disorders, autism, and learning disabilities in the UK. |
4,847 | |||
| 10 |
RSS Globalrssglobal.com
A portfolio of staffing brands specializing in workforce solutions across various sectors in the UK, Ireland, and Asia Pacific |
4,535 | |||
| 11 |
Murphymurphygroup.com
Provides engineering and construction services across transportation, water, power, natural resources, and property sectors in UK, Ireland, and Canada. |
4,078 | |||
| 12 |
Noventiqnoventiq.com
A global digital transformation and cybersecurity solutions provider connecting 80,000+ organizations, with a diverse portfolio and active M&A strategy for growth |
3,941 | |||
| 13 |
Places for Peopleplacesforpeople.co.uk
It is a leading social enterprise in the UK, focusing on community development, housing, leisure, and social impact initiatives. |
3,935 | |||
| 14 |
Endeavour Miningendeavourmining.com
Senior gold producer operating mines and development projects across West Africa, focusing on responsible mining and sustainable community value. |
3,594 | |||
| 15 |
City & Guildscityandguilds.com
Providing comprehensive skills training, credentials, and workforce development solutions through a global network to support employment and career growth. |
3,140 | |||
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. | |||||
| 16 |
London South Bank Universitylsbu.ac.uk
Provides engaging courses, industry connections, and real-world experience to empower diverse students to unlock their potential for success in work and life |
3,080 | |||
| 17 |
Stolt-Nielsenstolt-nielsen.com
Global provider of bulk-liquid and chemical logistics, transportation, storage services, and innovative sustainable aquaculture producing premium seafood species. |
3,069 | |||
| 18 | 3,022 | ||||
| 19 |
Sumersumer.co.uk
Championing small to medium UK and Ireland businesses by uniting expert firms to provide collaborative support and growth solutions. |
2,608 | |||
| 20 |
Blenheim Chalcotblenheimchalcot.com
A venture builder investing in high-growth sectors by providing funds, expertise, and infrastructure to build profitable, scalable companies globally |
2,370 | |||
| 21 |
Hachette UKhachette.co.uk
Publishing diverse books including fiction, non-fiction, children's books, educational materials, puzzles, gifts, games, e-books, and audiobooks globally. |
2,219 | |||
| 22 |
Aptia Groupaptia-group.com
Professional services firm combining technology and expertise to simplify pensions, health, and insurance management for businesses and individuals globally. |
2,209 | |||
| 23 |
Zen Educatezeneducate.com
This company is revolutionizing education recruitment by saving schools money on agency fees, providing skilled staff, and offering a user-friendly online platform |
2,147 | |||
| 24 |
ED&F Man Commoditiesedfman.com
Global provider of agricultural commodities including coffee, sugar, molasses, animal feeds, and fish oil with strong sustainability focus. |
2,142 | |||
| 25 |
Shaw Trustshawtrust.org.uk
A social purpose organization focused on challenging inequality, providing employment opportunities, and supporting social mobility through various services and support |
2,124 | |||
| 26 |
Collinson Groupcollinsongroup.com
Global company specializing in travel solutions, airport experiences, loyalty programs, insurance, and customer engagement for millions of consumers worldwide |
2,108 | |||
| 27 |
Clarion Housing Groupclarionhg.com
providing affordable homes to 360,000 people, building new homes annually, supporting residents through charitable programs focused on work, neighborhoods, and sustainability |
2,038 | |||
| 28 |
Urenco Globalurenco.com
Supplier of nuclear fuel enrichment services using centrifuge technology, ensuring safe, reliable, and sustainable nuclear fuel supply globally. |
2,027 | |||
| 29 |
London Borough of Barking and Dagenhamlbbd.gov.uk
A growing London borough investing in physical infrastructure, community, housing, a film studio, a university campus, and a Youth Zone Visit website for more information |
2,002 | |||
| 30 |
10N Collective10ncollective.com
Global collective of urbanism, architecture, and design experts focused on sustainable citymaking, environmental and social responsibility across continents. |
1,735 | |||
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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 12, 2026.
More company lists in London
- The largest companies in London 12,882
- Multinational companies in London 3,652
- Financial Services companies in London 1,862
- Financial services firms in London 1,824
- SaaS companies in London 1,615
- Professional services firms in London 1,248
- Software Development companies in London 1,217
- Retail chains in London 942
- IT Services and IT Consulting companies in London 693
- Companies with a mobile app in London 667
- Consulting firms in London 648
- IT services companies in London 607
- Subscription businesses in London 544
- Venture capital and private equity firms in London 539
- Marketing and communications agencies in London 533
- Retail Apparel and Fashion companies in London 498
- Advertising Services companies in London 480
- Companies with in-house R&D in London 477
- AI companies in London 456
- Investment Management companies in London 452
- Hotel and hospitality groups in London 445
- Luxury brands in London 428
- AI-native companies in London 407
- E-commerce companies in London 384
The same list elsewhere in United Kingdom
- Corporate groups and holding companies in the United Kingdom 666
- Corporate groups and holding companies in England 578
- Corporate groups and holding companies in Scotland 39