Mainframe Implementation Manager

Whitehall Resources currently require an experienced Mainframe Implementation Manager to work with a key client.**Please note this role falls INSIDE IR35**Role purpose: Plan, coordinate, and execute the end-to-end implementation of a mainframe product migration into production, ensuring a controlled, compliant, and low-risk cutover. Own the integrated deployment/cutover plan, readiness, and go/no-go governance across technology, operations, business, and third parties.Key responsibilitiesCreate and maintain the integrated implementation (deployment/cutover) strategy and plan covering scope, approach (big bang/phased), timeline, dependencies, and critical path.Lead cutover planning: detailed runbooks, rehearsal plans, roles/responsibilities, communications, checkpoints, and contingency/rollback.Coordinate release and change management activities (CAB submissions, implementation approvals, change records, stakeholder signoffs).Drive environment and operational readiness: capacity, access, monitoring, scheduling/batch windows, support model, service transition.Manage data migration implementation activities with clear sequencing, validation steps, reconciliation, and operational controls.Orchestrate dress rehearsals / mock cutovers, capture lessons learned and harden runbooks.Lead implementation governance: readiness reviews, RAID management, decision logs, and executive reporting.Coordinate hyper care/post-go-live: incident triage, defect backlog prioritisation, stabilisation metrics, and handover to BAU.Ensure alignment with risk/compliance/audit requirements (evidence packs, approvals, segregation of duties where required).Manage third parties/vendors involved in deployment (e.g., infrastructure, platform, data, app support, schedulers).Implementation strategy and Integrated Cutover PlanDetailed cutover runbooks (minute-by-minute where needed)Rehearsal plans and rehearsal outcomes/actions logChange/CAB artefacts and approval packReadiness criteria, go/no-go checklist, and decision logHypercare plan, support model, and BAU handover packImplementation closure report and lessons learnedRequired experienceProven Implementation/Cutover/Deployment Management on mainframe or large-scale legacy migrations.Strong understanding of z/OS production operations constraints: batch cycles (JCL), scheduling (e.g., Control-M/CA-7), DB2/IMS considerations, CICS regions, interface dependencies, and resilience/DR practices.Experience running dress rehearsals, coordinating cross-team cutovers, and leading go/no-go forums.Working knowledge of ITIL-aligned change, release, and incident management in regulated environments.

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