Biggest Data Breaches in the UK [Updated 2025] | UpGuard

This report ranks and summarizes the largest UK data breaches by impact, describing incidents (dates, scale, and compromised data) and their root causes — including malware on POS systems, unpatched vulnerabilities, misconfigurations, phishing, SQL injection, and ransomware — and notes regulatory responses and fines imposed by the ICO and other bodies.