Chartered Audit & Assurance · Est. 1994

Numbers people
stake their
reputation on.

Cornerstone is an independent audit and assurance firm for ambitious, scaling and listed businesses. Rigorous statutory audit, disciplined internal controls and corporate tax counsel — delivered with the gravitas your board and regulators expect.

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£4.2bnAssets under audit
ICAEWRegistered auditors
27Years of unqualified opinions
Corporate audit team in a glass boardroom reviewing financial statements with a city skyline beyond
Big-Four rigour
98%
Audits delivered ahead of deadline
0+
Audits Signed Off
£0bn
Assets Under Audit
0
Years Established
0%
Client Retention
What We Do

Assurance that
withstands scrutiny

From a first statutory audit through to complex group consolidations and regulatory examination, our partners bring discipline, independence and an unflinching attention to detail.

01

Statutory Audit

Independent external audit of financial statements under UK GAAP and IFRS — delivered to a defensible standard your board, lenders and shareholders can rely on.

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02

Internal Controls & Risk

Design, test and strengthen the controls that protect your business — SOX readiness, risk assurance and remediation programmes led by senior specialists.

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03

Corporate Tax

Corporation tax compliance and advisory that stands up to enquiry — group relief, R&D claims, transfer pricing and the disclosures that keep you clear of HMRC.

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Cornerstone Audit's corporate audit team collaborating over financial reporting
140 specialistsAcross audit, tax & risk
Why Cornerstone

Independence is not a box we tick

For ambitious companies, the audit is more than a compliance exercise — it is the signal that your numbers can be trusted. We hold that responsibility seriously, with the scepticism of a regulator and the partnership of a trusted adviser.

  • Partner-led, every engagement

    A named audit partner owns your file end to end — no anonymous teams, no surprise hand-offs at year-end.

  • Sector depth

    Financial services, technology, manufacturing and not-for-profit — we know the disclosures regulators look for in each.

  • Clean, audit-ready files

    Our process leaves your finance team better organised than it found them — a control environment that compounds in value.

The Cornerstone Method

A rigorous path to a clean opinion

Scoping

We assess materiality, risk and the control environment, then agree a clear timeline and single point of partner contact.

Fieldwork

Substantive testing, controls walkthroughs and data analytics across full populations — not just samples.

Review

Independent engagement quality review challenges every judgement before any opinion is formed.

Sign-Off

A clear audit opinion, a candid management letter and practical recommendations you can act on.

Margaret Ellison, Senior Audit Partner at Cornerstone Audit
Margaret Ellison FCASenior Audit Partner
Meet Your Partner

"A good audit asks the questions no one else will."

Margaret has spent twenty-two years signing audit opinions for listed groups, fast-scaling technology firms and regulated financial institutions. She leads Cornerstone's assurance practice with a simple conviction: that trust is earned in the detail.

Whether you are preparing for a first statutory audit, a transaction, or an FRC review, Margaret and her partners offer the independence, judgement and steadiness the moment demands.

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Trusted By Boards

Relied upon across regulated industry

MERIDIAN
ORBIS
VERTEX
NORTHWIND
HALCYON
ASCENT
QUADRANT
CEDARWOOD
PINNACLE
KESTREL
At Scale

Built for complexity, comfortable at the top floor

Group consolidations across multiple jurisdictions. Late-stage finance rounds. The scrutiny of a public listing. Cornerstone is structured to absorb complexity that would overwhelm a smaller practice — without losing the partner-led attention that defines us.

  • Group & consolidated audit

    Coordinated component audits, intercompany eliminations and a single, coherent group opinion.

  • IPO & transaction readiness

    Historical financial information, working capital reports and the assurance investors demand.

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Corporate glass office tower viewed from below against the sky
Client Confidence

The opinion that matters most is theirs

“
Cornerstone moved us from a qualified opinion to a clean one inside a single cycle. Their controls work alone repaid the fee several times over.
R
Rachel AdeyemiCFO, Meridian Holdings
★★★★★
“
We took our company public last year. The diligence and historical financials Cornerstone prepared stood up to every question the investment bank threw at them.
D
Daniel HartmannGroup FD, Vertex Technologies
★★★★★
“
As a regulated lender, our audit cannot wobble. In nine years Cornerstone has never once missed a deadline or softened a judgement. That is exactly what we pay for.
P
Priya NandakumarAudit Committee Chair, Orbis Finance
★★★★★
Insights

From the
assurance desk

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Begin the Conversation

Audit season is won before it begins

Whether you are appointing auditors for the first time or considering a change, a thirty-minute conversation with a Cornerstone partner is the right place to start.

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