Top Lean & SixSigma consulting firms in the UK 2023

Our ranking sets out to answer one basic question: what are the top consulting firms in the United Kingdom?

The consulting industry of the United Kingdom is home to hundreds of consulting firms – large, mid-sized, boutique and niche consultancies – serving clients across all industries and segments, and specialised in every conceivable area of expertise. Our Top Consulting Firms guide presents the industry’s leading players based on industry analysis and the views from both clients and consultants.

Yes, all firms ranked can showcase their recognition free of charge. Our Media Kit includes shields, graphics and artwork that support marketing and communication campaigns. Approval is not needed, feel free to make use of the assets.

An active company listing is part of a paid membership that is separate from the ranking methodology. See the page Join the Platform for details about our membership model. Firms that become a member can receive an active company profile within 1 day.

The Top Consulting Firms in the United Kingdom ranking is based on the ranking blueprint by Consultancy.org, our parent platform which conducts similar rankings across all regions and major countries.

The approach follows five key principles:

• Inclusive: All consulting firms that meet our ‘scope’ (see next question) and our part of our database qualify for the ranking. This happens automatically, there is no opt-in to join.
• No fees: There are no fees entry, assessment or qualification. This ensures the process is fully independent from commercial interests.
• Industry-wide: Our ranking is industry-wide, meaning that we assess firms active in all major areas of expertise (Strategy, Organization, Finance, Supply Chain, Digital, Sustainability, etc) and all major sectors (Financial Services, Public Sector, Energy, Healthcare, Retail, Manufacturing, etc).
• Holistic: Our ranking takes a 360-degree approach to evaluating firms. We gather insights from consultancy buyers, from consultants, conduct our own assessments, and draw on all credible information available in the public domain and research.
• Deep industry insights: While there are many consulting rankings around, at Consultancy.org we go beyond the surface. We understand the consulting market from the inside out. In fact, we claim that we know the consulting market better than anyone else.

A key starting point for our ranking is which types of firms can participate (‘scope’). Our Top Consulting Firms ranking centres around management consulting and digital transformation services, including fields which are directly adjacent to these areas.

Professional services that focus purely on the following areas are excluded from the process: Audit, Architecture, Communications, Creative, Engineering, Marketing, Investment Banking, IT managed services, BPO managed services, Public Relations, and Training.

For professional services with a blended service portfolio, such as accounting firms or IT companies with advisory practices, our ranking assesses and ranks the advisory side of the business.

Yes, all firms that have operations in the United Kingdom and meet the scope of our blueprint (see previous question) participate in the ranking. The ranking is fully inclusive and there are no fees throughout the process, from entry to qualification.

More than 1000 consulting firms were assessed for the latest edition of Top Consulting Firms in the United Kingdom.

Our approach takes an industry-wide and 360-degree approach to evaluating firms. We gather insights from clients, from consultants, conduct our own assessments, and draw on all credible information available in the public domain and research.

The ranking is based on two pillars: a survey of clients and consultants, and a capabilities assessment. Both factors have a weighting of 50%.

The views of clients and consultants are captured through Consultancy.org’s survey tool, which is open all year round.

Per 01/01/2025: More than 4,000 client reviews have been submitted by buyers of consulting services, and more than 15,000 peer reviews from consultants have been received across 80+ areas of service.

The capabilities assessment is based on an evaluation of five factors: firm capabilities, industry awards, prestige, thought leadership, and popularity on Consultancy.org. For each factor, data is gathered from Consultancy.org’s extensive database of firm capabilities and track record, from input received from consulting firms, and from credible external sources.

Firms that score above the threshold for ranking entry are included in the Top Consulting Firms in the United Kingdom list, with winners sorted across five levels: Diamond, Platinum, Gold, Silver and Bronze. Within each level, consultancies are sorted based on their average score, however, note that differences within a level can be negligible.

Firms that do not meet the threshold are excluded from the ranking. Across our rankings, over 80% of the advisory firms assessed do not make the ranking.

The Top Consulting Firms in the United Kingdom rankings feature leading firms based in the United Kingdom.

Out of more than 500 consulting firms assessed, only the leading players qualify for the ranking. If your firm is not ranked, it means that your firm did not gain sufficient positive data points to be included.

Consultancy.org’s ranking methodology is based on two main pillars: data from surveys, and a capabilities assessment. In short, it means that your firm did rank well enough on these pillars to included.  

Not being listed in the ranking could also mean that your firm was not part of our database. For questions on this, send us an email.

As with any ranking, assessing what defines a ‘top firm’ is an ambiguous task. The answer depends on a wide range of factors, and more than anything else, on the data that is available and analysed.

Consultancy.org’s ranking methodology is based on two main pillars: data from surveys, and a capabilities assessment. See the methodology for details.

Several ways to improve the score of your firm are:

• Sharing the survey tool with clients
• Sharing the survey tool with consultants and staff
• Sharing content on the firm, projects and thought leadership with our editorial team. We post this information on the website and this is automatically included in the database.
• Sharing awards and other achievements with our research team. This information is evaluated and inputted into the database.
• Providing our research team with a deck that showcases company credentials/testimonials. This information is evaluated and inputted into the database.

The next edition of Top Consulting Firms in the United Kingdom will be released in 2026.