Company lists · Data refreshed September 2026

Top 25 System administration outsourcing firms based in the United Kingdom

RevenueBase identified 779 system administration outsourcing firms headquartered in the United Kingdom as of September 2026 and tracks 6,627 professional contacts across them, including 2,999 with verified work emails and 398 with mobile numbers. London is the largest hub.

This list covers system administration outsourcing firms headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 6, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 6, 2026 86% judged on-target in blind review
779Companies
6,627Contacts tracked
2,999Verified emails
398Mobile numbers
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The 25 largest system administration outsourcing firms based in the United Kingdom

Ranked by team size
Top 25 of 779 system administration outsourcing firms based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 6, 2026. RevenueBase Smart Search rates how each company's information relates to system administration outsourcing firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#CompanyRevenueBase Smart SearchHeadquartersEmployeesContacts
1Indirect evidenceLondon, United KingdomHQ checked Sep 6, 20261,001-5,0001,039 contacts →

“Global business doesn’t have to be complicated.”

Source: company website · checked Sep 6, 2026
2Indirect evidenceBracknell, United KingdomHQ checked Sep 6, 2026201-500251 contacts →

“A&O IT Group, a global leader in managed IT services, brings over 50 years of expertise and operates in over 130 countries.”

Source: company website · checked Sep 6, 2026
3Indirect evidenceLondon, United KingdomHQ checked Sep 6, 202651-200141 contacts →

“Deepscale Technologies provide data center, enterprise & managed IT solutions across the globe that enhance how businesses operate.”

Source: company website · checked Sep 6, 2026
4Indirect evidenceGuildford, United KingdomHQ checked Sep 6, 202651-20093 contacts →

“ramsac provide so much more than just IT support.”

Source: company website · checked Sep 6, 2026
5Indirect evidenceLondon, United KingdomHQ checked Sep 6, 202651-20092 contacts →

“The costs for shifting to the cloud and juggling a hybrid environment continue to escalate due to rising support fees and expensive tech resources.”

Source: company website · checked Sep 6, 2026
6Indirect evidenceWooburn Green, United KingdomHQ checked Sep 6, 202651-20076 contacts →

“CST is an I.T.”

Source: company website · checked Sep 6, 2026
7Indirect evidenceCanterbury, United KingdomHQ checked Sep 6, 202651-20072 contacts →

“ADM Computing is an independent, family-owned IT services provider headquartered in Canterbury, supporting organisations across Kent, London and the South East since 1984.”

Source: company website · checked Sep 6, 2026
8Indirect evidenceBrentwood, United KingdomHQ checked Sep 6, 202611-5067 contacts →

“3Gi Technology is a global IT Managed Service Provider (MSP) offering enterprise level IT Professional Services to numerous companies all over the world.”

Source: company website · checked Sep 6, 2026
9Indirect evidenceBelfast, United KingdomHQ checked Sep 6, 202651-20066 contacts →

“We create, design, deliver and support informed & intelligent strategies to navigate shifting technology, keeping organisations like yours effective & secure.”

Source: company website · checked Sep 6, 2026
10Indirect evidenceManchester, United KingdomHQ checked Sep 6, 2026501-1,00063 contacts →

“Empowering Global Business with Seamless IT Excellence At Layers Logic IT Limited, we don’t just provide tech support-we build the digital backbone for global enterprises.”

Source: company website · checked Sep 6, 2026
11Indirect evidenceFenchurch Street, United KingdomHQ checked Sep 6, 202611-5054 contacts →

“We are an outsourced IT Services Provider, who specialise in delivering high quality end user support, and the design build and run of IT Infrastructure to the Alternative…”

Source: company website · checked Sep 6, 2026
12Indirect evidenceFinedon, United KingdomHQ checked Sep 6, 202611-5050 contacts →

“BSL, your personal IT partner.”

Source: company website · checked Sep 6, 2026
13Indirect evidenceOssett, United KingdomHQ checked Sep 6, 202651-20049 contacts →

“Concorde Technology Group is one of the UK’s leading Managed IT Services providers, specialising in Infrastructure Solutions, IT support, Cybersecurity, Communications and Cloud…”

Source: company website · checked Sep 6, 2026
14Indirect evidenceNorthampton, United KingdomHQ checked Sep 6, 202611-5041 contacts →

“RTS is a leading UK-based IT service provider, specialising in distributed networks, hosting services, and infrastructure consulting for medium to large enterprises.”

Source: company website · checked Sep 6, 2026
15Indirect evidencePaddock Wood, United KingdomHQ checked Sep 6, 202611-5040 contacts →

“Select Technology is one of the South East’s leading technology service providers, with 30 years of expertise in designing, implementing and supporting IT networks of all sizes.”

Source: company website · checked Sep 6, 2026
16Indirect evidenceLondon, United KingdomHQ checked Sep 6, 202651-20040 contacts →

“Phoenix47 is an IT infrastructure services company providing Support Desk, Managed Services and Professional Services.”

Source: company website · checked Sep 6, 2026
17Partial evidenceBurnley, United KingdomHQ checked Sep 6, 202611-5039 contacts →

“At Holker IT our aim is to improve our clients’ businesses through strategic advice, implementation and on-going support of IT systems and processes, from single to multi-server…”

Source: company website · checked Sep 6, 2026
18Indirect evidenceChorley, United KingdomHQ checked Sep 6, 202611-5038 contacts →

“Convene IT Ltd With over 15 years of experience in IT support services We we offer high quality business IT service, combining expertise and great customer service but without the…”

Source: company website · checked Sep 6, 2026
19Indirect evidencePeterborough, United KingdomHQ checked Sep 6, 202611-5038 contacts →

“If you're running a business, the last thing you need is slow, unreliable IT creating expensive problems.”

Source: company website · checked Sep 6, 2026
20Indirect evidenceAldridge, United KingdomHQ checked Sep 6, 202611-5037 contacts →

“Azets Technology Solutions supply a range of IT services and computer solutions which are designed to meet the needs of the SME, the IT support and services that Azets offer meet…”

Source: company website · checked Sep 6, 2026
21Indirect evidencePlymouth, United KingdomHQ checked Sep 6, 202611-5035 contacts →

“Acronyms is an IT support company offering a range of IT services, designed to save organisations time that they can spend on growing their own businesses.”

Source: company website · checked Sep 6, 2026
22Indirect evidenceSt. Albans, United KingdomHQ checked Sep 6, 202611-5034 contacts →

“Cheeky Munkey is a privately owned and managed IT support company based in St Albans, Hertfordshire, providing professional IT support within London and the South East.”

Source: company website · checked Sep 6, 2026
23Indirect evidenceWhitchurch, United KingdomHQ checked Sep 6, 202611-5034 contacts →

“Bristol's leading IT Support Provider, offering tailored IT solutions to meet your needs.”

Source: company website · checked Sep 6, 2026
24Partial evidenceBromsgrove, United KingdomHQ checked Sep 6, 202611-5032 contacts →

“Almost every business can save time and money with smart outsourcing from Go-To - how much depends on you.”

Source: company website · checked Sep 6, 2026
25Partial evidenceChesham, United KingdomHQ checked Sep 6, 202611-5031 contacts →

“Connect Systems are based in Chesham Bucks and were established in 1992 to provide professional IT services to the SMB market place.”

Source: company website · checked Sep 6, 2026

Showing 25 of 779 system administration outsourcing firms based in the United Kingdom

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System administration outsourcing firms based in the United Kingdom at a glance

As of Sep 6, 2026
45.3%Verified-email coverage
6.0%Mobile-number coverage
8.5Average contacts per company
1-10Median size (employees)
21.4%Largest-city concentration · London
Sep 6, 2026Page data refreshed

Companies by employee count

1-10
460
11-50
258
51-200
42
201-500
10
501-1,000
1
1,001-5,000
2

Freshness & accuracy

How recently the business emails on this list were verified

Email last verified

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among system administration outsourcing firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies
Companies headquartered in the United Kingdom whose own description of what they do matches “system administration outsourcing firms”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search
RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names system administration outsourcing firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude
Companies whose own description does not clearly place them among system administration outsourcing firms, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
Match quality
In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking
Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification
Every listed company carries at least one verified work email, 2,999 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh
This page's figures were pulled from the company graph on September 6, 2026. Lists refresh periodically as the graph is re-checked.
Corrections
Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

System administration outsourcing firms by metro

  • System administration outsourcing firms in London167

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names system administration outsourcing firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many system administration outsourcing firms are there based in the United Kingdom?

RevenueBase identified 779 system administration outsourcing firms headquartered in the United Kingdom as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

NSC Global, headquartered in London, tops this list with the largest team on record.

Which city has the most system administration outsourcing firms?

London leads with 167 headquartered companies, followed by Bristol (15) and Glasgow (11).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 2,999 verified decision-maker contacts tracked across these 779 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 6, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.