These London-based companies are primarily large-scale recruitment and staffing agencies, alongside significant players in HR services, business consulting, and IT consulting. They often focus on specialized sectors such as STEM, healthcare, and education. Noteworthy examples include Hays, a global specialist in recruitment and workforce solutions, AMS, which focuses on digital innovation in talent solutions, and Reed, a long-standing family-run recruitment agency.
A clear pattern among these companies is their strong presence in professional services, with many offering comprehensive solutions beyond traditional recruitment, such as advisory, outsourcing, and technology solutions. Most of these larger firms are headquartered in London, indicating the city's role as a central hub for these extensive service providers.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 | 55,656 | ||||
| 2 |
Hayshaysplc.com
Specialist recruitment and workforce solutions provider offering advisory services, career transitions, and employer brand positioning, with a focus on empowering people and businesses to succeed globally |
31,854 | |||
| 3 |
AMSweareams.com
Global talent solutions business specializing in sourcing, selecting, and retaining top talent through digital innovation, HR expertise, and a holistic approach to workforce management |
8,718 | |||
| 4 |
Supporting Education Groupsupportingeducation.com
Providing qualified teachers, support staff, professional development, and tailored services to improve education quality for schools and disadvantaged students. |
8,571 | |||
| 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 | 7,523 | ||||
| 7 | 6,669 | ||||
| 8 |
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 | |||
| 9 | 5,889 | ||||
| 10 |
Vialtovialtopartners.com
Global mobility ecosystem transformation through tax, immigration, compensation, and work strategy solutions for multinational organizations in 150+ countries |
5,717 | |||
| 11 |
Computer Futurescomputerfutures.com
A global STEM recruitment company connecting businesses with highly skilled IT talent for over 30 years through specialized IT market expertise |
5,349 | |||
| 12 |
RSS Globalrssglobal.com
A portfolio of staffing brands specializing in workforce solutions across various sectors in the UK, Ireland, and Asia Pacific |
4,535 | |||
| 13 |
Robert Waltersrobertwalters.co.uk
Providing recruitment, outsourcing, and advisory services globally to connect organizations with skilled professionals for permanent, temporary, or interim roles. |
4,508 | |||
| 14 |
FDM Groupfdmgroup.com
global business and technology consultancy powering tech innovation, launching careers, partnering with companies, emphasizing diversity and inclusivity worldwide |
4,132 | |||
| 15 |
UNKNOWNweareunknown.io
The company fosters diversity and creativity by facilitating connections, welcoming different perspectives to open up new possibilities in creative communities |
4,046 | |||
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 |
Blue Arrowbluearrow.co.uk
A leading UK staffing agency with expertise in placing candidates in various sectors, known for excellence in recruitment and employer recognition |
3,506 | |||
| 17 |
QX Global Groupqxglobalgroup.com
Partnering with mid-market organizations to reduce operating costs, improve efficiency, and scale confidently through sector expertise, process optimization, and technology. |
3,089 | |||
| 18 |
Londonagency.org.uk
Innovative recruitment agency based in London helps individuals find and apply for the latest job opportunities to start new careers |
2,884 | |||
| 19 |
NGA Human Resources, an Alight companyalight.com
Global provider of HR solutions, pioneering digital HR, payroll, compliance, and workforce data to enhance employee experiences, save costs, and transform organizations worldwide |
2,789 | |||
| 20 |
Ingeusingeus.co.uk
This organization provides services to improve skills, employment, wellbeing, and social inclusion, including employment programs, youth services, training support, and probation services |
2,546 | |||
| 21 |
The Black Apprentice Network (BAN)blackapprenticenetwork.co.uk
A network for black apprentices of African and Caribbean descent to connect, learn, and grow together, striving for continuous improvement |
2,529 | |||
| 22 |
Antal Internationalantal.com
Global executive search firm with extensive network, industry expertise, and local consultants providing talent solutions across multiple sectors worldwide. |
2,242 | |||
| 23 |
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 | |||
| 24 |
Tenth Revolution Grouptenthrevolution.com
Global leader bridging the tech skills gap by finding, training, and deploying talent through unified tech talent solutions for digital transformation success |
2,179 | |||
| 25 |
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 | |||
| 26 |
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 | |||
| 27 |
Bright Networkemployers.brightnetwork.co.uk
Connects top companies with bright graduates using data and technology to offer career opportunities and fulfill business talent needs. |
2,100 | |||
| 28 | 2,095 | ||||
| 29 |
GCSgcstechtalent.com
Global recruitment agency specializing in technology and commercial sectors, connecting innovators with businesses worldwide for over 30 years Part of nGAGE Specialist Recruitment since 2017 |
1,939 | |||
| 30 |
Protocol Educationprotocol-education.com
Specialist recruitment provider for the education sector, offering placement services for teachers, assistants, nursery nurses, instructors, and tutors across England |
1,819 | |||
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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.
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