Lead IT Infrastructure Platform Engineer

About IRIS IRIS Software Group is one of the UK's largest privately held software companies, trusted by 100,000+ businesses, schools and accountancy firms to keep their operations running. Our software pays 1 in 6 UK employees, supports over 12,000 schools, and is relied on by 91 of the top 100 UK accountancy firms. We're a Great Place to Work® certified employer, recognised for our commitment to well-being, inclusion and development - and we're growing fast. Take technical ownership of critical enterprise infrastructure platforms, lead complex and high-impact change, and make decisions that deliver a measurable uplift in engineering standards and technical capability. 1. The role and the impact you will make The Lead IT Infrastructure Platform Engineer provides lead-level technical ownership, design assurance and delivery leadership across enterprise infrastructure platforms and services. The role sets direction for assigned platforms or service areas, shapes standards and roadmaps, assures complex designs and leads high-impact implementations. It operates across organisational and technical boundaries, resolving ambiguity and influencing decisions while remaining sufficiently hands-on to maintain practical authority and support the most complex operational issues. This is an individual-contributor role with no line-management responsibility. Leadership is exercised through technical ownership, delivery coordination, influence, coaching and the quality of decisions and outcomes. The role balance is approximately 80% platform leadership, governance, design, project support and implementation, and 20% operational support. Success in this role is demonstrated through platform direction that holds up under scrutiny, design assurance that prevents costly rework, successful delivery of complex or high-impact change, and a measurable uplift in engineering standards and technical capability across the platforms it owns. 2. What you will be responsible for Provide lead-level technical ownership for assigned infrastructure platforms or service areas, setting direction within the agreed architecture and technology roadmap. Define and maintain platform roadmaps, lifecycle priorities, resilience objectives, improvement backlogs and technical standards. Assess cross-platform dependencies, strategic risks, technical debt and investment needs, presenting clear options and recommendations to decision-makers. Ensure platform decisions balance security, resilience, supportability, cost, delivery practicality and business outcomes. Lead the development and consistent application of infrastructure design standards, implementation patterns, engineering guardrails and operational acceptance criteria. Produce, review and assure high-level and low-level technical designs for complex or high-impact change. Provide constructive technical challenge and confirm that proposed solutions align with architecture, security, governance, operational and lifecycle requirements. Maintain clear decision records and ensure risks, exceptions, approvals and accountabilities are visible and understood. Lead the technical delivery of complex infrastructure projects and major platform improvements from discovery and design through implementation and transition. Shape technical scope, delivery approach, dependencies, sequencing, resource needs, acceptance criteria and implementation risks. Coordinate technical contributors across internal teams and suppliers, resolving ambiguity and escalating decisions at the appropriate point. Provide authoritative technical recommendations to project, architecture, security, service management and senior stakeholders. Ensure service transition is complete, including monitoring, controls, documentation, support models, recovery arrangements, knowledge transfer and ownership. Provide lead-level operational support for major incidents, high-risk problems and complex service issues affecting assigned platforms. Guide diagnosis and recovery, ensuring decisions are evidence-based, risks are controlled and communications are clear. Lead technical problem management and follow-through, ensuring lessons result in sustainable engineering or governance improvements. Review service trends and operational risks, prioritising improvements that reduce recurring demand and strengthen resilience. Participate in operational cover and planned out-of-hours work where required by the service. Provide technical direction, coaching and design guidance to engineers and peers without direct line-management responsibility. Build alignment across technical leads, architecture, security, service management, delivery teams, suppliers and business stakeholders. Represent the platform or service area in relevant governance, design and delivery forums. Raise the quality of engineering practice through reusable standards, peer review, knowledge sharing and clear documentation. 3. What you will bring Typically eight or more years in infrastructure engineering roles, including sustained experience operating at Senior level or equivalent. Extensive experience designing, implementing, governing and supporting enterprise infrastructure services in a complex organisation. Proven technical leadership of complex projects, major platform changes or multi-team technical initiatives from design through transition. Experience producing and assuring high-level and low-level designs, implementation strategies and operational acceptance criteria. Demonstrated ownership of platform roadmaps, lifecycle planning, technical standards, governance or service improvement portfolios. Experience leading technical response to major incidents and complex problems, with evidence of sustainable follow-through. Experience influencing architecture, security, service management, suppliers, project teams and senior stakeholders without relying on formal authority. Demonstrated ability to make sound decisions where requirements, ownership or technical direction are ambiguous. Deep practical knowledge in multiple enterprise infrastructure domains, with the credibility to make and defend complex technical decisions. Strong knowledge of Microsoft Azure infrastructure and platform services, Microsoft Entra ID, Windows Server, Active Directory, Exchange Server and Exchange Online. Strong knowledge of secure access and ZTNA/SASE architectures, for example Zscaler ZIA/ZPA, including migration from legacy VPN approaches and policy governance at scale. Broad capability across privileged access management, including PIM, virtualisation, Hyper-V, messaging security, Mimecast, backup and recovery, monitoring, networking, vulnerability management, hardening, resilience and business continuity. Ability to produce and assure high-level and low-level designs and translate architecture into implementable, supportable services. Strong understanding of security by design, architecture governance, service transition, operational acceptance, change control, incident and problem management. Practical understanding of PowerShell and infrastructure-as-code or DevOps tooling such as Terraform, Bicep and Azure DevOps, with the ability to promote standardised and repeatable delivery. Ability to balance technical quality, risk, cost, supportability, delivery constraints and business value. Ability to communicate complex risks, options and recommendations clearly to senior technical and non-technical stakeholders. Confidence working with suppliers and challenging proposals, assumptions, designs and delivery approaches where necessary. Calm, credible technical leadership, sound judgement and accountability for outcomes within the agreed scope. The ability to challenge constructively, create clarity for others and build trust across organisational boundaries without direct management authority. Why You’ll Love Working Here Impact: Your work will influence millions globally. Growth: Continuous learning and career development opportunities. Belonging: A culture that celebrates diversity and empowers every individual. Ready to Apply? Click Apply - we’re excited to learn about your unique perspective and experience. If you need adjustments during the process, let us know. We’re committed to making this opportunity accessible to everyone. What to expect from our hiring process Our process is designed to be fair, transparent and straightforward. Stages vary depending on the role — more senior positions may involve additional steps, and some areas include role-specific assessments such as a technical test or case study — but typically you can expect: Application review — we assess your experience and potential Initial call — a short conversation to learn about you and share more about the role Skills assessment — tailored to the position, e.g. case study, coding challenge or portfolio review Final interview — meet the team and explore how you'll make an IMPACT at IRIS We'll always walk you through the specific stages at the start of the process so you can prepare with confidence. If you need any adjustments or accommodations during the process, let us know, we’re committed to making this experience accessible for everyone.