Best Sustainability Consultancies in the UK (2026)

The UK market is led by the four Big Four (Deloitte, EY, KPMG, PwC — all Verdantix 2026 Green Quadrant Leaders), pure-play leaders ERM (London HQ; also Verdantix 2026 Leader), Anthesis Group, Ricardo Energy & Environment, WSP UK (Verdantix Leader), Ramboll UK (Verdantix Leader), Mott MacDonald, Arup, and AtkinsRéalis, plus mid-tier specialists including RSK Group, SLR Consulting and carbon-led EcoAct (an Atos company).

See the detailed firm cards above for positioning, geographic reach and best-for. For the carbon-specialism cut, see UK carbon consultants. For broader ESG, see UK ESG consultants.

Big Four firms (Deloitte, EY, KPMG, PwC) suit FTSE 100/250 transformation programmes, multi-jurisdiction reporting (UK SRS + CSRD + SEC), and where audit/assurance integration matters.

Pure-play firms (ERM, Anthesis, Ramboll) suit organisations wanting deep environmental and sustainability specialism without a financial-audit relationship, and where technical depth matters more than commercial breadth. Mid-tier specialists work best for sector-specific or regionally concentrated programmes.

The Verdantix Green Quadrant: Sustainability Consulting 2026 identified five Leaders with the most comprehensive sustainability consulting capabilities: Deloitte, EY, KPMG, PwC, and ERM.

In the adjacent Enterprise Carbon Management Software 2026 Green Quadrant, Cority and Sphera were also named Leaders — see the carbon reporting software guide.

Day rates vary widely: Big Four partners £2,500–£4,500/day; pure-play partners £1,800–£3,500/day; senior managers £900–£1,800/day; managers and consultants £400–£1,200/day.

Project fees scale: a SECR-scope first-year inventory might cost £15k–£40k; a UK SRS S2 readiness programme £75k–£250k+ depending on complexity; an enterprise CSRD/UK SRS multi-jurisdiction programme £300k+. We do not publish vendor fee tables — quotes are bespoke.

All 15 firms on this page cover UK SRS S2 readiness work, though depth varies. The Big Four and ERM have the deepest UK SRS S2 / IFRS S2 benches with cross-jurisdiction capability.

WSP, Ramboll and Anthesis are strong on the implementation side. Smaller and sector-specialist firms (Ricardo, Mott MacDonald) may suit narrower implementations in their sectors.

A sustainability consultancy delivers project work (UK SRS S2 readiness, SECR build, materiality assessment, transition plan delivery) — usually charged as project or day-rate fees.

A sustainability recruiter places candidates into in-house roles (Head of Sustainability, ESG Manager, CSO) — usually charged as percentage-of-salary placement fees. The two are commercially complementary, not substitutes.

Highly variable. A focused first-year SECR inventory typically takes 8–12 weeks. A UK SRS S2 readiness assessment 4–8 weeks. A full UK SRS S2 readiness + implementation programme 6–12 months.

Enterprise CSRD/UK SRS multi-jurisdiction programmes typically run 12–18 months. Materiality assessment work runs 4–8 weeks. Transition plan delivery 4–9 months — see transition plans.

B Corp certification is more common among smaller and pure-play firms than at the Big Four. The Green Recruitment Company (TGRC, on the carbon-led list) is the most prominent B Corp-certified carbon recruitment specialist.

Several of the consultancies above are signatories to other sustainability commitments. Check each firm's individual site for current certification status — the position changes.