13+
Years Experience
Independent. Opinionated. Effective.
Summit Advisory Group was founded in 2011 by former McKinsey and BCG partners who wanted to build a different kind of consultancy — smaller teams, deeper engagement, more accountability. We work with ambitious management teams, private equity sponsors, and boards navigating complexity: growth strategy, operational transformation, M&A integration, and interim leadership. We've delivered 140+ engagements across 14 sectors.
- Former McKinsey & BCG founding team
- Small teams, senior-led throughout
- Outcome fees available
- Embedded delivery — not just a report
Our Leadership Team
Former operators and advisers. We've sat in the chair you're sitting in.
William Thornton
Founding Partner — Strategy & Growth
Ex-McKinsey Principal. 20 years advising FTSE 100 and PE-backed businesses on organic growth and market entry across 11 sectors.
Dr. Aisha Okonkwo
Partner — Operational Transformation
Former COO at two FTSE 250 companies. Specialises in large-scale operational restructuring and technology-led transformation programmes.
Marcus Lindqvist
Partner — M&A & PE Advisory
Ex-BCG. 15 years leading buy-side due diligence, integration planning, and value creation for private equity firms across Europe and North America.
By ex-McKinsey & BCG partners
Across 14 sectors
All still actively client-facing
Management Today, 2023
Why Clients Choose Summit
Four things that consistently differentiate us from larger firms.
Senior People, Always
A founding partner leads every engagement personally. The person you meet in the pitch is the person doing the work — not a bait-and-switch.
We Say No When Appropriate
If we're not the right fit for your problem, we'll tell you. We'd rather refer you to someone better placed than take on work we can't do exceptionally well.
Embedded, Not Visiting
We don't parachute in, present slides, and leave. Where the work requires it, we embed — working alongside your team until the outcomes are real.
Skin in the Game
On many engagements, we tie a portion of our fee to outcomes. That's not common in consulting. We do it because we're confident in our work.
Work With People Who've Been There
Our partners have operated at board level. We bring that experience to every engagement.