Company lists · Data refreshed September 2026

Top 25 Impact consulting firms based in London, United Kingdom

Name: Impact consulting firms based in London, United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 30, 2026 3,580 companies tracked

RevenueBase identified 3,580 company matches for impact consulting firms associated with London, United Kingdom as of September 2026 and tracks 73,633 professional contacts across them, including 35,354 with verified work emails. Across the United Kingdom, London is the largest hub for this category.

This list covers company matches for impact consulting firms associated with London, United Kingdom, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 30, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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 RevenueBase SmartSearch · Exact Recorded Sep 30, 2026 How this list was built

3,580Companies

73,633Contacts tracked

35,354Verified emails

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The 25 largest impact consulting firms based in London, United Kingdom

Ranked by team size

Top 25 of 3,580 company matches for impact consulting firms based in London, United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 30, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#	Company	RevenueBase SmartSearch	Headquarters	Employees	Contacts
1	Ey-Parthenon	Exact match	London, United KingdomHQ recorded Sep 30, 2026	10001+	17,070 contacts →
	Exact match “Our unique combination of transformative strategy, transactions and corporate finance delivers real-world value – solutions that work in practice, not just on paper.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
2	ERM	Exact match	London, United KingdomHQ recorded Sep 30, 2026	5,001-10,000	9,119 contacts →
	Exact match “Sustainability is our business.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
3	SLR Consulting	Exact match	London, United KingdomHQ recorded Sep 30, 2026	1,001-5,000	3,848 contacts →
	Exact match “SLR is a committed partner in our clients’ sustainability journeys.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
4	Baringa	Exact match	London, United KingdomHQ recorded Sep 30, 2026	1,001-5,000	2,179 contacts →
	Exact match “Baringa is a global consulting firm that helps leaders drive meaningful change and create value.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
5	Brunswick Group	Exact match	London, United KingdomHQ recorded Sep 30, 2026	1,001-5,000	1,563 contacts →
	Exact match “Brunswick is a global advisory firm.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
6	Efficio	Exact match	London, United KingdomHQ recorded Sep 30, 2026	1,001-5,000	1,304 contacts →
	Exact match “Efficio is a global leader in procurement and supply chain management and transformation.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
7	Blackmont Consulting	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	1,221 contacts →
	Exact match “Blackmont Consulting provides 100% free advisory services to NGO´s, NPO´s and start-ups.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
8	Oc&c Strategy Consultants	Exact match	London, United KingdomHQ recorded Sep 30, 2026	501-1,000	1,011 contacts →
	Exact match “At OC & C Strategy Consultants we have more than 35 years of experience at unpicking the most complex business challenges with simple, uncommon sense™.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
9	Ricardo PLC	Exact match	London, United KingdomHQ recorded Sep 30, 2026	1,001-5,000	670 contacts →
	Exact match “Click the 'Follow' button and explore careers at Ricardo on our 'Jobs' and 'Life' tabs and at careers.ricardo.com.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
10	STEER	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	524 contacts →
	Exact match “Complex challenges.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
11	Frontier Economics	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	477 contacts →
	Exact match “We help companies with their biggest challenges – market strategies, regulatory reviews, competition inquiries.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
12	Analysys Mason	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	459 contacts →
	Exact match “Analysys Mason is the leading specialist consultancy, creating lasting value in technology-intensive industries, including telecoms, digital infrastructure, software, IT services…” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
13	Mercer UK	Exact match	London, United KingdomHQ recorded Sep 30, 2026	10001+	329 contacts →
	Exact match “At Mercer, A Marsh business, we’re helping our clients realize their investment objectives, shape the future of work, and enhance health and retirement outcomes for their people.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
14	Cartesian	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	302 contacts →
	Exact match “Cartesian is a specialist consulting firm focused on the global telecommunications, media, and technology industries and is now part of Bounteous, an AI services firm helping…” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
15	CIL Strategy Consultants	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	284 contacts →
	Exact match “CIL is a global growth strategy consultancy.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
16	Elixirr	Exact match	London, United KingdomHQ recorded Sep 30, 2026	501-1,000	275 contacts →
	Exact match “An award-winning global consulting firm working with clients across a diverse range of markets, industries and geographies.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
17	Transform	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	255 contacts →
	Exact match “Transform is a fresh alternative to Big Consulting.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
18	Moorhouse B Corp Certified	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	247 contacts →
	Exact match “We’re a dynamic consulting firm, focused on delivering change.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
19	Sheffield Haworth	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	244 contacts →
	Exact match “Sheffield Haworth is a global consultancy founded in 1993.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
20	Albany Beck	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	240 contacts →
	Exact match “Albany Beck is a client-first consulting firm helping financial services organisations deliver complex change and build capability, not dependency.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
21	CT Group	Exact match	London, United KingdomHQ recorded Sep 30, 2026	51-200	233 contacts →
	Exact match “CT Group is a global consultancy that uniquely combines research, intelligence, campaigns and advisory services, to deliver the results our clients need.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
22	The Erith Group	Exact match	London, United KingdomHQ recorded Sep 30, 2026	501-1,000	217 contacts →
	Exact match “Supported by a network of specialist consulting engineers, environmentalists and our own collective experience, our philosophy is simple: to provide a qualitative economic and…” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
23	Quantzig	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	216 contacts →
	Exact match “Quantzig is at the forefront of partnering with businesses to help them unlock transformative value through analytics solutions.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
24	Protiviti UK	Exact match	London, United KingdomHQ recorded Sep 30, 2026	201-500	206 contacts →
	Exact match “Welcome to the Protiviti perspective.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase
25	Radley Yeldar	Exact match	London, United KingdomHQ recorded Sep 30, 2026	51-200	198 contacts →
	Exact match “Radley Yeldar is an award-winning, independent London and Birmingham-based creative consultancy with more than 200 communications specialists.” Recorded in the RevenueBase company graph · Sep 30, 2026 · View company records in RevenueBase

RevenueBase SmartSearch

Describe a niche business in your own words. RevenueBase SmartSearch compares the meaning of your description with company business descriptions compiled in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit.

This list uses Exact for “impact consulting firms”. Each Exact match badge shows membership in that saved search; it is not an individual similarity score or a service-quality rating. Recorded descriptions are shown where available.

Showing 25 of 3,580 impact consulting firms based in London, United Kingdom

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Impact consulting firms based in London, United Kingdom at a glance

As of Sep 30, 2026

48.0%Verified-email coverage

20.6Average contacts per company

1-10Median size (employees)

Sep 30, 2026Page data refreshed

Companies by employee count

1-10

2,579

11-50

719

51-200

189

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured across the whole United Kingdom list rather than for London, so it is reported there. Company counts and contact totals on this page are exact for London, over 3,580 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
What qualifies: Company records associated with London, United Kingdom whose business descriptions match “impact consulting firms” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch: Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview: The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality: RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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 displayed company carries at least one verified work email. RevenueBase tracks 35,354 professional contacts with verified work emails across the full matched dataset. 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 30, 2026. Lists refresh periodically as the graph is re-checked.
Record context: Company records and descriptions can change. Check the company's website for its current services and locations.

Impact consulting firms by metro in the United Kingdom

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “impact consulting firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many impact consulting firms are there based in London, United Kingdom?

RevenueBase identified 3,580 company matches for impact consulting firms associated with London, United Kingdom as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Ey-Parthenon tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city in the United Kingdom has the most impact consulting firms?

London leads the United Kingdom with 3,580 company records, followed by Manchester (158) and Bristol (101).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 35,354 professional contacts with verified work emails tracked across these 3,580 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 30, 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 SmartSearch, 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.