1 API incident drove preventative actions across 250 APIs
Client: Nationwide Building Society
Nationwide is the world’s largest building society, with over 19 million members. Following its acquisition of Virgin Money UK PLC, Nationwide is connected with one in three people in the UK and is the second largest provider of mortgages and retail deposits. It is also a major provider of current accounts, credit cards, personal loans and business banking. Customers can choose to manage their finances in a branch, via mobile app, the internet, telephone, and post. Nationwide has around 25,000 employees and its head office is in Swindon, UK.
As a financial services provider owned by its members, not shareholders, Nationwide’s purpose is: Banking – but fairer, more rewarding, and for the good of society.
Challenge: only resolving one incident, not building wider resilience
Nationwide Building Society wanted its Major Incident Review process to deliver clearer learning and stronger
prevention. Major Incident Reviews (also known as Post Incident Reviews or postmortems) could take too long, and
discussions could be shaped by assumptions rather than evidence. Actions could also focus on the immediate
technical fix without fully addressing underlying causes, contributing factors or comparable risks elsewhere.
The aim was to strengthen Major Incident Management and Problem Management by making Root Cause Analysis
more consistent, focused and useful, then turn the findings into practical improvements across the wider technology estate to increase IT stability and resilience.
Solution: Implement Kepner-Tregoe Incident Mapping as the standard for Major Incident Reviews
The solution emerged when Nationwide Building Society saw Kepner-Tregoe experts apply Incident Mapping (a visual tool for Post Incident Reviews) live to one of Nationwide’s own P1 incidents. This proof of concept demonstrated the clearer, deeper insight the approach could produce and gave leadership the confidence to approve the business case for adoption.
The implementation was tailored to the different roles involved:
- Facilitators received deeper development, followed by coaching and observation.
- Regular contributors learned how to participate effectively in the review.
- Occasional attendees received a short explainer, so they understood the process and their role before joining a review.
Focused Incident Mapping was kept distinct from the wider incident review meeting. This gave the analysis enough structure and discipline while making the output easier to use in subsequent decision-making and improvement activity.
Incident Mapping gave teams a visual method to clarify the cause-and-effect chains, capture the circumstances that influenced impact, identify failed or missing controls and connect actions directly to what the evidence showed. According to the internal program framework, the approach became the new standard for Major Incident Reviews within two weeks of the initial workshop.
Results: a structured, repeatable process significantly improving IT resilience
The clearest example came from an incident involving a resource constraint affecting one API. A conventional
response might have stopped at a corrective action for that API. Incident Mapping made the wider causal chain,
circumstances and control gaps visible, leading to:
- capacity planning across approximately 250 APIs
- capacity monitoring across approximately 250 APIs
- timeout configuration reviews across key banking application customer journeys
- changes scheduled at times designed to reduce disruption if issues occurred
The value was not in the map itself, but in the broader insight and action it generated. Rather than correcting a single technical failure, Nationwide could identify underlying control gaps, recognize recurring themes and take preventative action across comparable services and future scenarios This evidence-based approach gave teams greater confidence in identifying control issues, enabled faster and more effective collaboration across departments, and helped focus improvement activity where it would have the greatest impact.
Key Results
| Measure | Reported Improvement |
|---|---|
| Time to detect | 66% reduction |
| Time to triage | 30% reduction |
| Actual time to resolve | 70% reduction |
| P1 incident volume | 40% reduction |
| Proactive control improvements identified | 17 => 42 |
| Controls identified per investigation | 2.5 => 3.5 |
Client Voice
“Implementing Incident Mapping was really transformational. Within two weeks of first learning it, we had teams working together in a genuinely collaborative, evidence-based way to drive prevention across the wider organization – and the remarkable before-and-after metrics show the impact.”
Ian Porter, Platform Manager, Nationwide Building Society
“The successful introduction of Kepner-Tregoe Incident Mapping has resulted in a more structured incident review, as well as providing far more consumable executive-level insights into complex issues. The approach improved proactive action identification, reducing major incident impact and improving overall resilience, processes, and controls across the organization. It is a great example of a backend process directly benefiting our customers and services.”
Paul Walsh, Group Director of IT Infrastructure and Service Delivery, Nationwide Building Society
At a glance
| Industry | Financial Services / Retail Banking |
| Organization | Nationwide Building Society – 19 million members and the UK’s largest branch network following the acquisition of Virgin Money UK |
| Challenge | Reviews resolved the incident in front of the team – but missed wider control gaps and opportunities to prevent similar failures |
| Solution | Kepner-Tregoe Incident Mapping proved live on a P1 incident, then implemented as an evidence-based, collaborative review process within two weeks |
| Result | 66% faster detection, 30% faster triage, 70% faster resolution and 40% fewer P1 incidents – with one API incident driving preventative action across approximately 250 APIs |
Could this work for your organization
Major Incident Reviews are only one application. The same structured approach to root cause analysis and learning is used in:
- Problem Management and Proactive Problem Management
- CAPA (Corrective and Preventive Action) programs in pharmaceuticals and life sciences
- Enhanced Root Cause Analysis in manufacturing and critical infrastructure
If your post-incident reviews feel like a formality rather than a driver of genuine improvement, it may be time to look at the process itself.
Turn major incident learning into stronger operational resilience
Talk to Kepner-Tregoe about strengthening Post Incident Reviews through structured Root Cause Analysis and Incident Mapping.
Next Steps
- Book an individual consultation with a KT expert
- Request a live demo of a Major Incident Review using Incident Mapping
- Explore training options: Incident Mapping for Post Incident Reviews, Root Cause Analysis, Major Incident Management
FAQs
How can organizations improve their Post Incident Review process?
Organizations can improve Post Incident Reviews by using a structured, evidence-based approach to identify causal chains, contributing circumstances, and failed or missing controls. Methods such as Kepner-Tregoe Incident Mapping help teams move beyond fixing the immediate technical issue and identify preventative actions that can reduce the risk of similar incidents across other systems and services.
How can Post Incident Reviews help reduce recurring IT incidents?
Post Incident Reviews can reduce recurring incidents by identifying not only the immediate cause, but also wider control gaps and comparable risks across the IT environment. At Nationwide Building Society, analysis of one API incident led to preventative capacity planning and monitoring actions across approximately 250 APIs, demonstrating how lessons from one incident can be applied more widely.
How can Root Cause Analysis improve Major Incident Management KPIs?
Structured Root Cause Analysis can improve Major Incident Management by helping teams identify causes and control gaps more consistently and turn those findings into targeted preventative actions. In a Nationwide Building Society case study, the reporting period showed a 66% reduction in time to detect, 30% reduction in time to triage, 70% reduction in actual time to resolve, and 40% reduction in P1 incident volume.
What is Incident Mapping and how is it used in Post Incident Reviews?
Incident Mapping is a visual, evidence-based method for analyzing complex incidents. It helps teams clarify cause-and-effect chains, capture the circumstances that influenced an incident’s impact, identify failed or missing controls, and connect corrective and preventative actions directly to the available evidence.
How can financial services organizations improve IT resilience after a major incident?
Financial services organizations can improve IT resilience by using incident findings to identify risks and control weaknesses beyond the system where the original failure occurred. Applying structured Post Incident Reviews and Root Cause Analysis enables teams to translate lessons from individual incidents into preventative actions across comparable services, processes, and future scenarios
How quickly can teams learn Kepner-Tregoe Incident Mapping and start using it in Post Incident Reviews?
Teams can learn Kepner-Tregoe Incident Mapping and be ready to apply it as part of their Major Incident Review process within a matter of weeks. Nationwide completed a combined workshop and coaching program over two weeks and was then ready to successfully implement KT Incident Mapping as standard work across the organization.