This document outlines a case of the SECONOMICS modelling framework aimed at differentiating different policy problems for critical national infrastructure. The document works through an analysis of differentiating between regulatory types for electricity transmission and builds on previous work documented in Deliverables D2.2, D2.3 and D6.1. For analysis of the underlying tool architecture see deliverable D8.2 for programming details. D8.3: Complete Design of Prototype: Security Problem Modeller Description of deliverable: Complete Design of Prototype: Security Problem Modeller: D8.3 will describe the complete design of the integration of the Security Problem Modeller developed in WP6. Additionally first prototypes of the tool integration will be implemented.