Senior Software and Security Engineer

As a Senior Software Engineer in deltaflare’s Technology team, you provide proficient, largely independent capabilities across the systems and products the business owns.

You will evaluate, specify and design new technical platforms, build technical proofs of concept and customer driven demonstrators to a production standard, while acting as a credible independent challenge to our internal Development and Assurance teams, advising across architectures, scaling, and platform security.

You will work mostly independently, under the Head of Technology, escalating only complex or strategic decisions, while providing technical quality oversight and mentoring to Graduate Engineers and Engineers.

Success in this role means owning your technical outcomes, strengthening deltaflare’s technical estate, contributing to customer technical engagements, and helping ensure technical risk is surfaced, evidenced and resolved before delivery, across teams in our business.

WHAT YOU’LL DO

Your main accountabilities: what you will own and be responsible for delivering.

• Lead the evaluation and proving of new technology before delivery, including software development for proofs of concept, demonstrators and structured technical assessments.

• Iterate customer technical and security commitments into practical controls, configuration, software changes and mitigations for the systems you own.

• Provide independent technical challenge to Development and Assurance, reviewing source code, infrastructure-as-code and architecture against requirements and good practice.

• Front direct technical engagement with customers, regulators and industry bodies for owned systems and areas, preparing materials and evidence that stand up to scrutiny.

• Design, implement and maintain architectural controls across deltaflare’s AWS based systems, identifying, remediating and evidencing security and resilience issues across the business.

• Oversee and review work produced by Graduate Engineers and Engineers, giving constructive, standards-based feedback that raises the technical bar.

• Deepen your primary technical specialism while building cross-functional awareness across OT cybersecurity, cloud security, assurance and UK Critical National Infrastructure.

Essential: what you must bring on day one

• Several years’ hands-on engineering experience delivering complex technical and security work independently and to a high standard.

• Proven ability to review, critique and constructively challenge technical work produced by others.

• Strong working knowledge across networking, Linux, architectural security, infrastructure as code, containers and cloud platforms.

• Software development ability in at least one language, with the judgement to assess system-level impact of code produced by others.

• Clear technical communication skills, including the ability to engage credibly with customers, regulators and senior stakeholders.

• A degree in Computer Science, Software Engineering, Network Engineering, Cybersecurity or a related STEM discipline, or equivalent capability demonstrated through substantial industry, project-based or self-directed experience.

Desirable: not essential, but will help you stand out

• Professional-level certifications such as CISSP, cloud security, professional-level cloud or ISC2 certifications.

• Experience in OT/ICS security, regulated industries or Critical National Infrastructure environments.

• Applied experience of NIS2, NCSC CAF, IEC 62443, OT/ICS protocols or architecture, or mentoring junior engineers.

WHO YOU ARE

You will thrive here if you are technically rigorous, calm under pressure and comfortable challenging work on evidence rather than hierarchy. We need someone who owns outcomes, shares knowledge freely, and understands that protecting critical national infrastructure means being thorough even when delivery pressure is high.

• You hold the line on technical risk, even when it is uncomfortable, and will not sign off on undocumented or partially validated work.

• You challenge constructively regardless of seniority, default to transparency and help others improve through practical feedback.

• You ask “why”, test assumptions and look for safer, better ways to adopt new technology rather than relying on “how we’ve always done it”.

• You take ownership of outcomes in complex technical environments and know when to act independently and when to escalate.

• You are genuinely interested in OT cybersecurity, critical infrastructure and the regulatory environment that shapes the sector.

Pulled from the full job description

• Annual leave

• Company pension, * Any relevant project, portfolio or certification details that help evidence your technical experience

• Optionally: A short covering note explaining why this role and deltaflare’s mission are of interest

For an informal conversation before applying, please contact K. Fouwels, Head of Technology.

Pay: £83,000.00-£95,000.00 per year

Ability to commute/relocate:

• London, Greater London: reliably commute or plan to relocate before starting work (preferred)

Application question(s):

• Can you functionally write and evaluate code in at least one programming language?
• Describe a system you designed or significantly re-architected? What were the constraints, what did you choose, and what did you deliberately give up?
• Describe a time you reviewed someone else’s software, design, or architecture and decided the work wasn’t safe to proceed with. What did you find, and what was the outcome?

deltaflare is the UK’s specialist in Operational Technology (OT) cybersecurity for Critical National Infrastructure (CNI) operators. We deliver NIS2 and CAF compliant protection across gas, electricity, water, renewable technology and transport network, the systems that keep the country running.

We work where IT meets industrial reality: inside control rooms, substations and treatment works, helping CNI operators navigate the unique challenges of securing hyper-connected physical systems without disrupting the operations that millions of people depend on.