The UK Cloud Compliance Landscape in 2025
UK enterprises selecting between Amazon Web Services (AWS) and Microsoft Azure must weigh compliance capabilities against the backdrop of evolving UK data protection law. The Data (Use and Access) Act 2025, which came into force in June 2025, introduces nuanced changes to UK GDPR whilst the ICO continues robust enforcement.
Both providers maintain comprehensive compliance programmes. AWS supports 143 security standards and compliance certifications, whilst Azure offers over 100 compliance offerings. For UK-specific requirements, the distinction lies not in breadth but in implementation detail and ecosystem integration.
UK Data Residency: Region Comparison
Both providers operate dedicated UK infrastructure, though architectural differences affect disaster recovery and availability patterns:
AWS eu-west-2 (London): Three availability zones within a single UK region. AWS pairs London with Dublin (eu-west-1) for cross-region replication, meaning DR configurations may involve data leaving UK borders unless explicitly restricted.
Azure UK South and UK West: Two UK regions paired together, enabling geo-redundant disaster recovery entirely within UK borders. UK South offers three availability zones; UK West currently operates without AZs but serves as the paired DR region.
For organisations requiring strict UK-only data residency, Azure's UK region pairing provides a distinct advantage. AWS customers must implement additional controls to prevent data replication to Dublin.
ICO Compliance and UK GDPR Controls
The Information Commissioner's Office requires organisations to demonstrate accountability under UK GDPR Article 5(2). Both providers offer compliance tooling, though approaches differ:
AWS Compliance Approach:
UK GDPR Addendum incorporated into AWS Service Terms automatically
CISPE Code of Conduct certification for 100+ services
AWS Artifact for on-demand compliance documentation
Granular IAM controls with AWS Organizations SCPs
AWS Config rules for continuous compliance monitoring
Azure Compliance Approach:
Microsoft Data Protection Addendum with UK-specific provisions
EU Data Boundary controls extended to UK regions
Customer Lockbox preventing Microsoft engineer data access
Azure Policy for organisation-wide compliance enforcement
Microsoft Purview for data governance and classification
Certification and Accreditation Comparison
For UK public sector procurement, both providers meet essential requirements. Shared certifications include ISO 27001, 27017, 27018, 27701, SOC 1/2/3 Type II, Cyber Essentials Plus, G-Cloud 14, and PCI DSS Level 1.
AWS Differentiators: NCSC Cloud Security Principles attestation, forthcoming AWS European Sovereign Cloud, FIPS 140-2/140-3 validated cryptographic modules.
Azure Differentiators: HITRUST CSF certification, Azure Government UK for higher classifications, deeper Microsoft 365 integration for unified compliance.
Security Controls: Encryption and Access
AWS: Encryption at rest is not enabled by default for all services. Organisations must explicitly enable encryption for S3 buckets, EBS volumes, and RDS instances. AWS KMS provides key management with CloudHSM available for FIPS 140-2 Level 3 requirements.
Azure: AES-256 encryption enabled by default for most services. Transparent Data Encryption (TDE) automatically protects Azure SQL databases. Azure Key Vault integrates natively with Microsoft services, reducing configuration complexity.
For UK enterprises with limited cloud security expertise, Azure's default-on encryption reduces the risk of misconfiguration—a common factor in ICO enforcement actions.
Pricing and Cost Considerations
UK region pricing for both providers carries approximately 10% premium over US regions. Direct cost comparison depends heavily on workload patterns:
Storage: Azure typically 15-20% cheaper for blob storage in UK regions
Compute: AWS offers more granular instance sizing; Azure provides better value for Reserved Instances with Microsoft EA
Egress: Both charge similar rates; Azure offers free egress to Microsoft 365 services
Hybrid Benefit: Azure Hybrid Benefit can reduce costs 40%+ for organisations with existing Windows Server/SQL licences
Recommendation Framework for UK CIOs
Choose AWS when: Your organisation operates multi-cloud architecture, requires the broadest service catalogue (200+ services), has high DevOps maturity, or runs primarily Linux-based workloads.
Choose Azure when: Your organisation relies heavily on Microsoft 365/Dynamics 365, UK-only disaster recovery is required, you hold Microsoft Enterprise Agreements, need hybrid cloud with on-premises Windows Server, or prefer default encryption with simpler compliance controls.
