Steve Varley, who led EY UK until 2020, will serve as chairman, while Marissa Thomas, formerly PwC UK’s chief operating officer, will be chief executive.

Recruitment for Unity Advisory is under way, with a launch anticipated by June. The firm aims to challenge the Big Four by offering tax, accounting services, technology consulting, and M&A advice, primarily to mid-sized UK companies with revenues between £500m and £1.5 billion, particularly those with private equity backing.

Crucially, Unity will not have an audit practice, allowing it to operate without the conflict-of-interest concerns and heavy regulatory scrutiny associated with auditing, which often affect the Big Four. Mr Varley told the Financial Times the firm will be “super client-centric,” utilise AI, have low administrative costs, and crucially, “no conflicts”.

The absence of an audit arm and lower central costs could permit different fee structures, potentially including more performance-based fees.

The venture reflects a growing trend of private equity investment in the professional services sector, traditionally dominated by partner-owned models. Warburg Pincus managing director David Reis noted the “substantial market opportunity for disruption” in how finance teams are serviced.

Mr Varley, who left EY in late 2023, and Ms Thomas, who departed PwC in February 2024 after being passed over for the senior partner role, plan to hire staff with Big Four experience.