| # | Company | Employees |
|---|---|---|
| 1 |
UK Civil Servicegov.uk
This company implements government policies, delivering essential public services in the UK |
238,504 |
| 2 |
NHS Englandengland.nhs.uk
This organization collaborates with NHS Improvement to enhance care delivery, transparency, and services for patients in England while prioritizing efficiency and accountability |
59,120 |
| 3 | 42,697 | |
| 4 |
Department for Work and Pensions (DWP)gov.uk
The company is responsible for welfare, pensions, child maintenance, and benefits, aiming to reduce poverty, promote work, and ensure financial security for all |
33,465 |
| 5 |
UK Ministry of Defencegov.uk
The company works to protect the security and interests of the United Kingdom, providing necessary training, equipment, and support for the Armed Forces |
30,901 |
| 6 |
Ministry of Justice UKgov.uk
Government department responsible for justice system administration, legal affairs, courts, prisons, and public safety in the United Kingdom. |
20,603 |
| 7 |
Transport for Londontfl.gov.uk
London-based transportation company leading in providing diverse travel options, focusing on customer feedback, technology innovation, and large-scale investments for city-wide mobility improvements |
18,658 |
| 8 |
Post Office Ltdpostoffice.co.uk
operates largest UK retail network with 11,500 branches and a major digital presence, focusing on customer service and innovation |
17,058 |
| 9 |
Guy's and St Thomas'β NHS Foundation Trustguysandstthomas.nhs.uk
Provides high-quality healthcare services, clinical excellence, research, and community care through multiple hospitals and partnerships in London. |
11,655 |
| 10 |
Barts Health NHS Trustbartshealth.nhs.uk
Managing five London hospitals including specialist heart and cancer services while providing safe quality medical care for diverse and deprived local communities. |
10,093 |
| 11 | 9,410 | |
| 12 |
Imperial College Healthcare NHS Trustimperial.nhs.uk
Delivers acute and specialist medical care, conducts biomedical research, and provides clinical education for healthcare professionals across five London hospital sites. |
7,248 |
| 13 |
House of Commonsparliament.uk
This company supports and educates on the functions of elected MPs in representing the public, legislating, and scrutinizing the Government |
6,657 |
| 14 |
King's College Hospital NHS Foundation Trustkch.nhs.uk
A large and busy Trust providing care to 1 million people, with a commitment to excellence and a global reach strategy in place |
6,425 |
| 15 |
BBC Studiosbbcstudios.com
BBC Studios is a leading content studio and channels & streaming business known for top-quality, award-winning shows and global distribution of British content |
6,277 |
| 16 |
Bank of Englandbankofengland.co.uk
Maintains monetary and financial stability to promote the public good and benefit of the people in the United Kingdom. |
5,947 |
| 17 |
Royal Free London NHS Foundation Trustroyalfree.nhs.uk
A leading London NHS Trust providing high-quality healthcare across three hospitals, focusing on clinical excellence, research, and patient-centered care |
5,782 |
| 18 |
University College London Hospitals NHS Foundation Trustuclh.nhs.uk
Provides acute and specialist medical services across six London hospitals, focusing on patient care, education, and biomedical research. |
5,737 |
| 19 |
HM Courts & Tribunals Service (HMCTS)gov.uk
This organization oversees the administration of courts and tribunals in England, Wales, Scotland, and Northern Ireland, ensuring fair and efficient access to justice |
5,284 |
| 20 | 4,789 | |
| 21 |
Civil Aviation Authoritycaa.co.uk
Regulation and oversight of aviation safety, consumer protection through ATOL, development of aviation technology and environmental standards. |
4,334 |
| 22 |
Thames Valley District School Boardtvdsb.ca
A public school board serving a diverse region in Ontario, focused on progressive growth, student achievement, equity, and community partnerships |
4,232 |
| 23 |
North London NHS Foundation Trustnorthlondonmentalhealth.nhs.uk
Providing community-based and inpatient mental health care services across North London boroughs, supporting local and wider populations. |
3,983 |
| 24 |
Great Ormond Street Hospital for Children NHS Foundation Trustgosh.nhs.uk
National centre providing specialist healthcare for children with complex, rare, and congenital conditions, focusing on research and teaching partnerships. |
3,938 |
| 25 |
Central and North West London NHS Foundation Trustcnwl.nhs.uk
Integrated healthcare provider in Central and North West London, also serving Milton Keynes, Surrey, and beyond Offers diverse services for various health needs |
3,898 |
| 26 |
Dorchester Collectiondorchestercollection.com
Collection of luxury hotels and residences known for unique character, cultural significance, and providing sophisticated, legendary guest experiences worldwide. |
3,763 |
| 27 |
East London NHS Foundation Trustelft.nhs.uk
Provider of mental health care, innovation, and improvement services in East London and beyond Earning awards and striving for excellence |
3,749 |
| 28 |
Chelsea and Westminster Hospital NHS Foundation Trustchelwest.nhs.uk
A NHS Foundation Trust running two hospitals and community services, providing outstanding healthcare to a million people with innovative outreach programs |
3,504 |
| 29 |
UK Health Security Agencywww.gov.uk
The company is an executive agency responsible for planning, preventing, and responding to external health threats at national and global levels |
3,430 |
| 30 |
London Borough of Lambethbeacons.ai
Providing planning, social work, housing, and education services to a diverse community of over 300,000 residents and businesses. |
3,148 |
| 31 |
Islington Councilislington.gov.uk
Local government focused on affordable housing, job investment, environmental health, youth development, and fostering safe, inclusive community connections. |
2,986 |
| 32 |
Richmond and Wandsworth Councilsjobs.richmondandwandsworth.gov.uk
Deliver high-quality public services across two London boroughs, supporting communities through innovation, collaboration, and adapting to change. |
2,965 |
| 33 |
The Royal Marsden NHS Foundation Trustroyalmarsden.nhs.uk
Cancer diagnosis, treatment, research, and education, operating two hospitals in London and Surrey, and partnering with The Institute of Cancer Research. |
2,930 |
| 34 |
London Fire Brigadelondon-fire.gov.uk
Full-time firefighters and support staff protect people and property from fire across Greater London, operating 24/7 emergency response system. |
2,894 |
| 35 |
Care Quality Commissioncqc.org.uk
Independent regulator ensuring safe, effective, compassionate, and high-quality health and adult social care services in England. |
2,847 |
| 36 |
Channel 4channel4.com
Free-to-air UK broadcaster offering multiple TV channels and streaming, commissioning independent content, focusing on young audiences and British film investment. |
2,807 |
| 37 |
London Ambulance Service NHS Trustlondonambulance.nhs.uk
This company is the busiest emergency ambulance service in the UK, providing free emergency and urgent healthcare in London |
2,724 |
| 38 |
Lewisham and Greenwich NHS Trustlewishamandgreenwich.nhs.uk
Healthcare provider serving over 666,000 people across three boroughs, offering quality care, innovative services, and support for staff well-being and development |
2,668 |
| 39 |
South Western Railwaysouthwesternrailway.com
A train company focused on improving customer experience through investments in new trains, station upgrades, and ticket options |
2,647 |
| 40 |
HM Treasurygov.uk
Government ministry responsible for managing public spending and shaping UK economic policy direction |
2,260 |
| 41 |
Whittington Healthwhittington.nhs.uk
Integrated care organization providing hospital and community services to 500,000 people in north London, focusing on delivering personalized, coordinated, and high-quality healthcare |
2,173 |
| 42 |
Royal Brompton and Harefield hospitalsrbht.nhs.uk
Largest UK centre specializing in advanced heart and lung treatments, surgeries, and research, attracting patients and experts worldwide. |
2,094 |
| 43 |
Moorfields Eye Hospital, Londonmoorfields.nhs.uk
A leading eye hospital in London providing clinical care, research, and education, treating a wide range of eye conditions and conducting ophthalmic research |
2,054 |
| 44 |
British Transport Policebtp.police.uk
national police force ensuring safety and security across railways, underground, trams, and cable car systems during passenger journeys |
2,039 |
| 45 |
Southeastern Railwaysoutheasternrailway.co.uk
A transportation company operating train services into London from Kent and East Sussex, with a large network and high-speed trains |
2,039 |
| 46 |
Royal Borough of Kensington and Chelsearbkc.gov.uk
The organization aims to provide high-quality services in Kensington and Chelsea to improve residents' lives, environment, housing, and community resources |
1,968 |
| 47 |
South West London and St George's Mental Health NHS Trustswlstg.nhs.uk
Provider of mental health services in south west London, with a staff of over 2,000 serving 11 million people Offers care, treatment, education, and research partnerships |
1,878 |
| 48 |
Central London Community Healthcare NHS Trustclch.nhs.uk
A leading community healthcare organisation providing services across London and Hertfordshire, focused on supporting patients to live healthier lives at home |
1,855 |
| 49 |
UK National Audit Officenao.org.uk
Independent public spending watchdog in the UK, supporting Parliament in holding government accountable and improving public services through high-quality audits |
1,760 |
| 50 |
Tatetate.org.uk
A public institution with four major galleries showcasing British and international art to increase public enjoyment and understanding |
1,743 |
| 51 |
Greater London Authoritylondon.gov.uk
Strategic authority implementing mayoral policies, supporting assembly oversight, managing finance, communities, growth, housing, resources, and communications for London. |
1,737 |
| 52 |
Natural History Museumnhm.ac.uk
The company is a leading science research center and visitor attraction with vast collections, expertise, and a mission to tackle global challenges |
1,731 |
| 53 |
Medicines and Healthcare products Regulatory Agencygov.uk
Regulating medicines and medical devices to improve health, supported by science and research, with career opportunities in central London and Hertfordshire |
1,718 |
| 54 |
Ofcomofcom.org.uk
Regulating UK communications, ensuring fair home phone and mobile services, overseeing TV, radio, and content, protecting consumers, promoting access to technology |
1,700 |
| 55 |
North Middlesex University Hospital NHS Trustnorthmid.nhs.uk
A busy acute hospital in London providing a wide range of medical services and specialist care, including cancer treatment and support services |
1,488 |
| 56 |
Royal Marinesroyalnavy.mod.uk
An elite fighting force within the Royal Navy, specializing in rapid response to global threats and security challenges, including ship-to-ship operations |
1,423 |
| 57 |
Capital City Collegecapitalccg.ac.uk
London's largest further education college group offering exceptional education, training for students and businesses through popular colleges and bespoke training programs |
1,403 |
| 58 |
Victoria and Albert Museumvam.ac.uk
Museum family promoting creativity and design through exhibitions, education, conservation, research, and a vast collection spanning 5,000 years. |
1,402 |
| 59 |
National Crime Agency (NCA)nationalcrimeagency.gov.uk
The company is focused on protecting the public from serious and organized crime by targeting and pursuing high-risk criminals in the UK |
1,363 |
| 60 |
The British Librarybl.uk
National library providing access to over 170 million items including historical documents, contemporary media, and digital content for inspiration and research. |
1,326 |
| 61 |
The British Museumbritishmuseum.org
Museum preserving and exhibiting global cultural artifacts, offering educational exhibitions and events to engage millions of visitors annually. |
1,321 |
| 62 |
Cafcass (Children and Family Court Advisory and Support Service)cafcass.gov.uk
Cafcass represents children in family court cases, advocating for their safety and best interests, ensuring their voices are heard and welfare is safeguarded |
1,282 |
| 63 |
Historic Englandhistoricengland.org.uk
This organization protects and celebrates England's historic environment, working with communities to inspire interest, care, and conservation for future generations |
1,278 |
| 64 |
NICE - National Institute for Health and Care Excellencenice.org.uk
Independent assessment and guidance development for health and social care professionals to improve outcomes and promote best practices. |
1,231 |
| 65 |
Acasacas.org.uk
Impartial experts providing information, training, and dispute resolution services to support good employer-employee relationships and ensure compliance with UK employment laws. |
1,081 |
| 66 |
The Crown Estatethecrownestate.co.uk
Managing diverse land, property, and seabed assets across the UK, supporting sustainability, economic growth, and returning profits to government. |
1,044 |
| 67 |
Science Museum Groupsciencemuseumgroup.org.uk
A group operating multiple museums focusing on science, technology, engineering, and medicine using a national collection to inspire visitors |
960 |
| 68 |
Barnet Enfield and Haringey Mental Health NHS Trustnorthlondonmentalhealth.nhs.uk
Provider of integrated mental health and community health services in Barnet, Enfield, and Haringey, serving 12 million people with over 3,300 staff across 20 sites |
946 |
| 69 |
College of Policingcollege.police.uk
Setting police standards, accrediting training, promoting best practices, supporting partnerships, and leading ethics and integrity in policing. |
888 |
| 70 |
Sport Englandsportengland.org
Promoting inclusivity in sports and physical activities by utilizing funds from the Government and The National Lottery to support participation for all |
876 |
| 71 |
General Pharmaceutical Council (GPhC)pharmacyregulation.org
An independent regulator ensuring safe and effective care in pharmacy services by setting standards, inspecting pharmacies, and protecting public confidence |
875 |
| 72 |
The Insolvency Servicegov.uk
The company provides a framework for dealing with financial failure and misconduct, maintains insolvency laws, delivers public services, and enforces regulations |
858 |
| 73 |
Security Industry Authoritywww.gov.uk
Regulating the private security industry in the UK by licensing individuals and managing the Approved Contractor Scheme to ensure high standards |
836 |
| 74 |
Assala Energyassalaenergy.com
An energy company in Africa focused on acquiring mature oil and gas assets, increasing production and reserves through field redevelopment |
776 |
| 75 |
City of London Policecityoflondon.police.uk
Policing a unique financial district with focus on preventing crime, tackling fraud, and ensuring business continuity in a global center. |
753 |
| 76 |
Imperial War Museumsiwm.org.uk
The company tells the stories of people involved in conflicts, explores war causes and impacts, and engages audiences worldwide through various platforms |
753 |
| 77 |
The National Lottery Community Fundtnlcommunityfund.org.uk
Distributor of National Lottery funding supporting community-led projects for resilient, inclusive, and sustainable communities across the UK |
740 |
| 78 |
British International Investmentbii.co.uk
A UK-based development finance institution and impact investor, partnering with businesses in Africa, Asia, and the Caribbean to create inclusive economies |
706 |
| 79 |
The Tavistock and Portman NHS Foundation Trusttavistockandportman.ac.uk
Specialist mental health trust offering services for children, families, young people, and adults, along with academic training, research, and consultancy |
701 |
| 80 |
SEFE Marketing & Trading Ltdsefe-mt.com
Leading European energy trading company offering physical & financial trading of LNG, gas, power, environmental products, and hydrogen with risk management services |
643 |
| 81 |
NHS Resolutionresolution.nhs.uk
An arm's length body of the Department of Health and Social Care providing expertise to the NHS in claims management, performance advice, and contracting dispute resolution |
608 |
| 82 |
The National Gallerynationalgallery.org.uk
A prestigious institution housing Western European paintings from the 13th to 19th centuries, striving for excellence in collection care, access, and education |
598 |
| 83 |
UK Export Financeukexportfinance.gov.uk
Support UK companies with finance and insurance to secure, complete, and receive payment for export contracts sustainably and cost-effectively. |
590 |
| 84 |
Genomics Englandgenomicsengland.co.uk
collaboration with NHS to integrate genomic testing into routine healthcare, supporting research and development of targeted medicines |
566 |
| 85 |
General Dental Councilgdc-uk.org
Regulating dental professionals in the UK, ensuring high standards, quality education, updated practices, and protecting patient rights through registration and complaints support |
558 |
| 86 |
Tube Linestfl.gov.uk
Maintenance and upgrade of infrastructure on Jubilee, Northern, Piccadilly lines, including tracks, trains, stations, and safety services. |
552 |
| 87 |
Nest Pensionsnestpensions.org.uk
Established in 2010, this UK company provides a low-cost pension scheme to help individuals save for retirement with high quality services and investment solutions |
499 |
| 88 |
London & Partnerslondonandpartners.com
Promotes London business growth through innovation announcements, business launches, expansions, news, free events, and reports. |
427 |
| 89 |
NS&Insandi-corporate.com
A leading UK savings provider with unique government backing, aiming to become the most trusted in the country through innovation |
405 |
| 90 |
Financial Services Compensation Schemefscs.org.uk
The company offers a reliable compensation service to enhance trust in the financial services sector |
369 |
| 91 |
Digital Catapultdigicatapult.org.uk
Accelerate deep technology adoption by partnering with businesses, investors, and academia to create market pathways and support UK innovation growth. |
307 |
| 92 |
LPPIlppi.co.uk
Investment management and pension services provider for local government and public sector pension schemes, focusing on reducing deficits and improving returns. |
222 |
| 93 |
Westminster Adult Education Servicewaes.ac.uk
Provides diverse adult education courses including Art, Health, Social Care, and ESOL with flexible study options and community partnerships. |
167 |
| 94 |
London Stadiumlondon-stadium.com
Transformed London Stadium into a versatile venue for music, sports, and entertainment, creating a world-class environment to bring fans together |
141 |
| 95 |
CDC Group plcbii.co.uk
A company specializing in international investments, providing services in various financial sectors with a focus on British markets |
127 |
| 96 |
London LGPS CIV Limitedlondonciv.org.uk
manages and pools local government pension scheme assets to achieve economies of scale, efficiency, and improved investment performance |
75 |
| 97 |
China Taiping Insurance (UK) Co Ltduk.cntaiping.com
Underwriting general insurance and reinsurance policies, specializing in property, accident, liability, marine, and aviation insurance for UK and European markets. |
57 |
| 98 |
London Pensions Fund Authoritylpfa.org.uk
Management of a defined benefit pension fund with extensive assets, active in sustainable investment and collaboration with public sector pension networks. |
36 |
| 99 |
Start Up Loans Companystartuploans.co.uk
Provide government-backed personal loans up to Β£25,000 with fixed interest and free mentoring to help UK startups grow successfully. |
34 |
| 100 |
London Treasurylondontreasury.org
A London-based investment manager specializing in ultra short fixed income and GBP-denominated alternatives for the Greater London Authority and its partners |
30 |
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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 Oct 24, 2026.
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