Head of Architecture | C# ​/.NET | Legacy Decomposition | Azure

Head of Architecture | C# / .NET | Legacy Decomposition | Azure | Fully Remote | Exclusive to Optimal Salary:
Up to £100,000  excellent benefits

Contract:

Permanent Start: ASAP - 4 weeks notice maximum for this one Working Model:
Fully Remote (UK) Eligibility:
No sponsorship - you must hold a British passport or Indefinite Leave to Remain (ILR) Requirement:
Seeking a senior architect or principal-level professional with a proven track record of breaking down complex legacy platforms. Must have a solid background in Azure and C#/.NET, no exceptions . Non-Negotiables - Please only apply if you have ALL of the following Core Technologies: C# and .NET (Framework and modern) SQL Server at scale Azure (cloud experience essential) RabbitMQ, Redis, CI/CD Able to read any part of a large codebase to understand what it does (you will not write production features day-to-day) Environment:
Significant experience as a senior architect or principal engineer on a complex, multi-year platform - not greenfield Proven experience evolving a live system under delivery pressure Hands-on with gradual decomposition of legacy systems: strangler patterns, service boundary definition, data migration sequencing Experience operating in a regulated environment (PCI DSS, ISO 27001, Cyber Essentials or equivalent) Proven ability to influence without authority - you have driven standards adoption across teams that did not report to you Key

Skills:

Ability to point to a forum, guild, or chapter model you have run and the outcomes it produced Strong written and verbal communication across registers - whiteboard with engineers, plain-language summary with commercial stakeholders Experience mentoring and growing senior engineers so their judgement develops under your influence, not their dependency on you Comfortable defining engineering standards, integration patterns, and cross-service contracts that reflect real practice

Role Overview This is an exclusive role to Optimal, and a brand-new, high-impact hire for an established, profitable UK software business running a mission-critical, high-volume transactional platform that processes billions of transactions in a regulated environment. You will be the senior-most individual contributor in the engineering function and the person accountable for technical coherence across the whole platform. Your job is to stand up the architecture function from scratch: the target architecture, the ARB process, the Architecture Guild, and the engineering standards that shape how the whole org builds.

This is not a line-management role, and it is not a hands-on feature-development role. It is the technical authority the engineering teams unify behind - a practitioner who reads code, joins design sessions, and gets standards adopted through influence, not command. The function already has strong Principal Engineers, Tech Leads, and a Principal Security Engineer. Your job is to channel that capability into one coherent direction.

Key Responsibilities Define and maintain a living 12-24 month target architecture: what stays, what moves, when, and what the service boundaries are Build the ARB process - templates, cadence, and the culture where decisions are recorded, traceable, and asked for rather than worked around Run the Architecture Guild as your channel for driving standards into teams that do not report to you Sequence decomposition: a principled backlog of which parts of the monolith to tackle first, in what order, and why Drive the pivot from infrastructure-level monitoring to outcome-based SLOs (latency, error rate, user impact) Partner with the Principal Security Engineer on technical security posture Publish engineering standards - coding conventions, integration patterns, observability, cross-service contracts - developed with the senior engineers so they reflect real practice Support technical hiring: calibration, interview panels, and shaping the technical bar Nice to Have Experience in regulated, payments-adjacent, or similarly compliance-heavy product domains Defining and driving an SLO-based observability posture across multiple services Hands-on microservices / AKS / Kubernetes at production scale Architecture certification (TOGAF, Azure Solutions Architect, or equivalent) Background in App Sec or secure design review If you tick all of the above and you thrive on influence over authority, we would love to hear from you.