We are not looking for a generalist. We need a specialist who understands that migrating a payment engine is a high-wire act. You will own the bridge between our legacy Mainframe and target platforms, ensuring that every message from legacy MT to modern MX flows with 100% integrity. Core Responsibilities Architectural Ownership: Lead the 'Strangler Fig' migration of legacy payments, defining the data architecture, extraction logic, and target mappings. Scheme Mastery: Act as the SME for UK and International schemes including BACS, FPS, SWIFT (ISO 20022 / MX), and SEPA. Control & Compliance: Design and enforce CISA-aligned audit frameworks and CASS regulatory controls to ensure zero-loss migration. Pragmatic Legacy Integration: Navigate the 'documented vs. actual' reality of Mainframe systems, building executable solutions within existing technical constraints. Technical Requirements Payments Flow Expertise: Ability to demonstrate design leadership across the full lifecycle: Gateway/Connectivity (MQ, SWIFT), Core Processing Logic, and Downstream Reconciliation. ISO 20022 Transition: Direct experience with MT-to-MX translation and the November 2026 structured address enforcement standards. Leadership: Proven track record in PMI (Post-Merger Integration) or similar large-scale payments transformation programmes. Randstad Technologies is acting as an Employment Business in relation to this vacancy.