The Rise of Unity Advisory: A Disruption Playbook Against the Big Four

In what may become one of the most strategically significant shakeups in the UK’s professional services sector, two of the most senior figures from EY and PwC—Steve Varley and Marissa Thomas—have launched Unity Advisory, a boutique advisory firm aiming to challenge the dominance of the Big Four. Backed by up to $300m from private equity giant Warburg Pincus, Unity is positioning itself as a lean, AI-led, conflict-free alternative for UK CFOs and mid-cap corporates.

From a financial markets perspective, this move is less about a new firm and more about the convergence of capital and talent to disrupt an entrenched oligopoly. The advisory and accountancy services market in the UK, valued at £45bn+, has long been under pressure due to audit-related regulatory scrutiny, conflicts of interest, and stagnating innovation. Unity, which eschews audit services entirely, is a timely response to this.

MY TAKE: Strategic Timing Meets Structural Opportunity

This isn’t simply a vanity project by former Big Four leaders—it’s a structural thesis on the future of professional services. Several dynamics are at play here:

1. Private Equity's Infiltration of Professional Services

   Following Cinven's acquisition of a majority stake in Grant Thornton UK in 2023 and Warburg’s earlier backing of Steve McGill in insurance, Unity is the next instalment in PE's attempt to unlock value from legacy advisory models. The traditional partnership model, though lucrative, has proven inflexible for long-term investment in tech infrastructure and scalable service delivery.

2. The Audit-Consulting Divide is Now an Asset, Not a Liability

   The Financial Reporting Council (FRC) and global regulators have increasingly scrutinised the audit-consulting duality within the Big Four, pressuring firms to ringfence operations. Unity’s choice to avoid audit entirely allows them to circumvent this regulatory drag and pursue higher-margin consulting, M&A, and tax work, unfettered by compliance conflicts.

3. Targeting the Mid-Market: The Sweet Spot for Disruption

   Unity plans to serve private equity-backed firms with revenues between £500mn and £1.5bn—a segment often underserved or deprioritised by the Big Four due to scale or cross-selling limitations. This is a shrewd play. These firms are cash-generative, acquisitive, and agile, often requiring nimble advisors who understand both finance and operational transformation.

4. AI as a Core Enabler

   Rather than bolting AI onto legacy systems (a common pain point in the Big Four), Unity is launching as an AI-native platform. Expect value-based pricing models, rapid diagnostic tools for cost take-out strategies, and data-driven M&A advisory. If executed well, this could offer clients a 30–50% faster turnaround time on high-impact advisory engagements.

Final Thought: Could This Reshape Valuations in the Sector?

If Unity succeeds in capturing market share—particularly in high-growth sectors like tech, fintech, and private equity—there could be wider implications for valuation multiples in the professional services space. We could see a re-rating of firms that pivot away from audit-heavy models toward tech-enabled, private equity-aligned advisory practices. In the long run, Unity’s model might even set the blueprint for what a next-gen global advisory house looks like.

Bottom Line: Unity Advisory isn’t just another boutique—it’s a calculated, well-capitalised disruption effort that leverages ex-Big Four credibility, private equity backing, and AI-native infrastructure. As the Big Four brace for more scrutiny and slower agility, Unity could emerge as a serious contender—particularly in the mid-market M&A and transformation advisory space.

Let’s keep an eye on how this plays out in H2 2025. If Unity can scale without diluting quality, we might just be witnessing the birth of a new tier in professional services.