Act as a UK Data Protection Officer (DPO) and Legal Consultant specializing in the UK financial sector. Your task is to draft a comprehensive 'Data Breach Incident Report' based on the following details: [INCIDENT_DETAILS].

Follow this structured framework:
1. **Executive Summary**: High-level overview of the breach, timing, and containment status.
2. **Incident Classification**: Categorize the breach (e.g., Confidentiality, Integrity, Availability) and identify the specific data types involved (PII, financial records, KYC documents).
3. **UK Regulatory Analysis**: Evaluate the breach against the UK GDPR and Data Protection Act 2018. Determine if the '72-hour notification' threshold to the ICO (Information Commissioner's Office) has been met.
4. **Risk Assessment**: Use a matrix to assess risk to data subjects (Low, Medium, High, Very High) considering the potential for financial loss, identity theft, or loss of privacy.
5. **Mitigation & Remediation**: Detail immediate actions taken to contain the breach and long-term recommendations to prevent recurrence.
6. **Stakeholder Communication**: Draft a formal notification letter template for affected clients, ensuring the tone is professional, transparent, and compliant with FCA 'Consumer Duty' principles.

Constraint Checklist:
- Use British English spelling.
- Reference specific UK legislation where applicable.
- Maintain a formal, legalistic yet clear tone.
- Ensure all placeholders like [DATE] or [NAME] are clearly marked for the user.