Senior Security Engineer - Contract

About this role

What is Flagstone? Flagstone is many things. An online savings platform, reinventing how individuals, businesses, and charities manage, protect, and grow their cash. A diverse group of people, bound by a collaborative spirit, and shared purpose. And lastly, a thriving, profitable business – where smart people do their best work. Each definition shares a common thread: our unique culture. It’s our pride and joy. And our competitive advantage.

A feel for our culture: To revolutionise the savings market, we need to be at our best. But high performance takes more than talent – it takes a culture of kindness, respect, and growth. That’s why we’re building a diverse, inclusive community, where your voice is heard and valued. Where, with close support and room to develop, you can surpass even your own expectations. And be rewarded for it. We may not change the world, but we can change the world of financial technology.

And all it takes is a winning mix of drive, talent, and empathy. Our culture celebrates all three. But enough about us. Let’s talk about you. About the team Security Engineering is a team of five covering cloud security, detection, and security operations. They work directly in the Azure estate and are close to the infrastructure, not abstracted behind a policy layer. The team runs Microsoft Sentinel, Defender XDR, and Defender for Cloud, and manages tooling through infrastructure-as-code.

They run a quarterly penetration test programme and are continuously building out our detection and response capability. It's a small team with broad scope, which means your work is visible, your opinions are heard, and there are meaningful problems for our engineers to work on. This is a contract role, so we're looking for someone who can hit the ground running. You'll bring immediate impact and add value from day one, working independently without a long ramp-up.

Your work will be visible, and the problems you solve will matter. Does this sound like you? You're a senior security engineer who operates credibly across cloud security, detection tooling, and incident response, without being narrowly specialised. You own meaningful parts of the security stack, contribute hands-on to Azure cloud hardening, and show up reliably when incidents need investigating or pen test cycles need coordinating.