About 1 Sequence Cyber

Independent. Practitioner-led. Globally engaged.

A UK-credentialled cybersecurity consultancy. We deliver compliance audits and security testing directly — QSAs, lead Penetration Testers, ISO 27001 lead auditors, and vCISOs in the room from scoping through attestation.

Who we are

A UK-incorporated consultancy with global reach.

1 Sequence Cyber Limited is a UK-incorporated cybersecurity consultancy — Companies House 16021460, headquartered in Milton Keynes. We are a PCI SSC-listed QSAC, ISO 27001 and ISO 9001 certified, and Cyber Essentials Plus assessed.

Our practitioners hold the credentials we sell against: QSAs for PCI DSS, lead Penetration Testers for CREST-aligned testing, ISO 27001 lead auditors, and seasoned vCISOs. We do not resell vendor platforms and we do not subcontract delivery to generalists. The named credential on the engagement is the practitioner who shows up.

LEADERSHIP

Practitioner-led leadership.

Our consultants and operators run engagements end-to-end.

Ronald Williams
CEO
Senior QSA, lead auditor, multi-framework engagement governance.
J Sebastian
CTO, Director of Operations
Platform architecture & technical strategy.
Stephen Hancock
Principal QSA
PCI DSS QSA, ROC reporting, SAQ assessment.

Sujith MP
Director of Professional Services
PCI DSS, ISO 27001, multi-framework engagement delivery.
Sminu Vargheese
CFO
Financial governance and commercial structuring.

Practice areas

16 services. Compliance and security under one roof.

Compliance

PCI DSS
ISO 27001
NIS-CAF
SWIFT CSP
Data Privacy / GDPR
HIPAA
GRC
ASV Scanning

Security

Penetration Testing
SOC as a Service
Security Incident Response
Secure Payment Solutions
Business Continuity & DR
OT Cyber Security
SMB Security Assessment
vCISO

The full list sits in the Services menu.

Reach

Engaged across four regions, expanding into a fifth.

Engaged by merchants, acquirers, and enterprises across the UK, Europe, US and APAC to deliver audits, harden defences, and sustain compliance. Active expansion into the Middle East.

Delivery model

We deliver every engagement directly.

We do not resell. We do not generalise. Three principles govern every engagement we sign.

Direct delivery
No resale, no margin stack from third parties. The consultancy you contract with is the consultancy that delivers.
Practitioner-led
The QSA on the call is the QSA on the engagement. The lead Penetration Tester runs the test. The lead auditor signs the report.
Audit-defensible
Every output stands up to assessor scrutiny. Methodology drawn from PCI SSC, CREST, ISO/IEC and NIST published references.

Accreditations