Security Monitoring & Detection Engineering Lead

Job Description

Help protect the trust behind investing.

At AJ Bell, we believe investing should feel good. For our customers to feel confident about their investments, they need to know that the technology, data and services behind them are secure.

As our Security Monitoring & Detection Engineering Lead, you'll play a critical role in making that possible. You'll be the principal technical authority for our Security Monitoring & Detection Engineering capability, shaping how we monitor, detect and respond to threats across AJ Bell.

This is a senior, hands-on technical role. You'll own the architecture and engineering of Microsoft Sentinel and our wider security monitoring estate, lead complex investigations and technical incident response, and turn real-world adversary behaviour into effective detection and response.

You'll work across Cyber Defence Operations, Technology and our Managed Security Service Provider (MSSP), bringing people, technology and intelligence together to reduce the potential for customer, operational, financial and regulatory harm.

The role would particularly suit an experienced detection engineering, security operations, red-team, purple-team or offensive-security leader who wants to combine deep technical expertise with meaningful leadership and measurable security outcomes.

What you'll do

Set the direction for security monitoring

You'll provide the technical leadership and direction that keeps our monitoring and detection capability effective, relevant and aligned to the threats we face.

• Own the technical direction, quality and delivery performance of Security Monitoring & Detection Engineering, translating CDO priorities into a clear roadmap for monitoring, detection, investigation and response.
• Lead the architecture, engineering and continued development of our SIEM solution, ensuring the SIEM remains resilient, scalable, cost-effective and aligned with AJ Bell’s technology estate and threat profile.
• Define and govern the onboarding of security telemetry across on-premises, Microsoft Azure, AWS and third-party services, ensuring log sources address genuine visibility gaps and provide reliable value for detection and investigation.
• Own the detection engineering lifecycle across requirements, design, testing, deployment, tuning, performance assessment and retirement, supported by version control, peer review and controlled release practices.

Build better detection and response

You'll lead the engineering discipline behind our detection capability, continually improving how we identify, investigate and respond to threats.

• Lead the development of analytics rules, hunting queries, workbooks and automated investigation and response workflows.
• Own the operational effectiveness of security solutions managed by CDO ensuring configurations, integrations, detections and workflows deliver measurable security outcomes.
• Drive threat-informed defence with Cyber Threat Intelligence and Cyber Threat Exposure Management, translating relevant threat actors, campaigns, TTPs, IOCs, critical vulnerabilities and attack paths into detections, targeted threat hunts and automated defensive actions.
• Identify and deliver appropriate uses of automation and AI across detection engineering, enrichment, investigation and response, measuring the resulting improvement in quality, speed, consistency or coverage.

Lead complex investigations and incidents

When a significant threat emerges, you'll provide the senior technical judgement needed to understand what has happened, contain the threat and reduce its impact.

• Act as the senior technical escalation point for complex, ambiguous and high-severity security events, leading investigations through scoping, attack reconstruction, business-impact assessment, containment and resolution.
• Experience investigating malicious code, identity compromise, business email compromise, fraud-related intrusion, data exfiltration, cloud compromise or third-party intrusion.
• Lead technical response within CIRT during declared cyber incidents, coordinating the internal team, MSSP and relevant technology functions in accordance with the firm’s incident-management processes to contain threats and reduce business impact.
• Build and improve investigation and response playbooks for priority threat scenarios, and lead tabletop, purple-team and practical exercises that test detection coverage, technical readiness and coordination with relevant business functions.

Measure and continually improve performance

You'll make sure our security capability is not only technically strong, but demonstrably effective.

• Maintain an evidence-based view of service performance through agreed KPIs, KRIs and operational MI, identifying material variations, recurring failure points and capacity constraints, and driving corrective actions through to a measurable outcome.
• Maintain an evidence-based view of alert demand, detection quality, MTTA, MTTR, investigation outcomes, service capacity and recurring failure points, using these measures to prioritise and demonstrate improvement.
• Lead service reviews with key security vendors and providers, assessing delivery against expected outcomes and driving actions that maximise the contribution of existing investment to CDO’s Detect, Defend and Respond objectives.
• Report functional performance, incident readiness, monitoring coverage, material risks and capability constraints to the Head of Cyber Defence Operations, providing clear recommendations and action plans.

Bring people and partners together

You'll help create one joined-up monitoring and response capability across our internal team and MSSP, while developing the technical capability of those around you.

• Operate the internal team and MSSP as one integrated monitoring and response capability, setting clear expectations for investigation quality, escalation consistency and response effectiveness, and addressing service issues before they affect security outcomes.
• Develop Senior Analysts and junior team members through technical leadership, investigation review, practical training and structured knowledge transfer, creating credible succession within the function.

On-Call Requirement

This role participates in the Cyber Defence Operations on-call rota, providing senior technical leadership during significant out-of-hours security events and declared cyber incidents.

What we're looking for

We're looking for a technically credible security leader who can combine deep hands-on expertise with strong judgement, clear communication and the ability to turn threat intelligence and adversary behaviour into practical defensive capability.

Essential

• Extensive experience across security monitoring, SIEM engineering, detection engineering and incident response within a complex enterprise environment.
• A strong record of designing, building, operating and evolving Microsoft Sentinel as a production security monitoring and response capability.
• Deep expertise in KQL and the engineering of analytics rules, hunting queries, workbooks and threat-informed detection content.
• Extensive experience designing telemetry architectures and onboarding security data, including connectors, parsing, normalisation, retention, ingestion health, data quality and cost management.
• Experience integrating cloud-hosted services and security telemetry into central monitoring and leading investigations and incident-response activity across AWS, Azure environments.
• Strong knowledge of Microsoft Defender XDR across endpoint, identity, email and cloud security, including the correlation of evidence across the Microsoft security ecosystem.
• Experience designing and implementing automated investigation and response workflows using Azure Logic Apps, APIs, PowerShell, Python or comparable orchestration technologies.
• Experience establishing and governing a production detection engineering lifecycle, including testing, peer review, version control, controlled deployment, performance monitoring and retirement.
• Experience operating and materially improving enterprise security platforms such as Mimecast, Varonis, or comparable email and data-security technologies.
• Experience translating adversary behaviour, threat intelligence, incident findings, exposure data and offensive-security results into improved detection and response capability.
• Strong written and verbal communication, with the ability to translate complex threats, incidents and capability gaps into clear business implications, recommendations and decisions.

Preferred

• Experience leading red-team, purple-team or offensive-security activity and converting identified attack paths and adversary techniques into improved detection and response.
• Experience in financial services, or a regulated environment.

Qualifications

Relevant certifications or completed professional training may include:

• Security Blue Team, Blue Team Level 2, BTL2
• GIAC Certified Incident Handler, GCIH
• GIAC Certified Intrusion Analyst, GCIA
• CREST Registered Intrusion Analyst, CRIA
• Certified Red Team Operator, CRTO
• OffSec Certified Professional, OSCP
• OffSec Wireless Professional, OSWP
• EC-Council Certified Ethical Hacker, CEH

About AJ Bell

At AJ Bell, we believe investing should feel good. Whether you're looking for an ISA, pension or dealing account, whether you want to invest with the help of a financial adviser or do it yourself, we have easy-to-use solutions to suit people from all walks of life.

We're one of the UK's fastest-growing investment platform businesses, trusted by everyone from professional financial advisers to first-time investors.

Today, over 762,000 customers trust us to manage more than £121.5 billion of assets. By continually striving to make investing simpler and more accessible, we're helping more people take control of their financial futures.

Behind that customer experience is a technology and security environment that people need to be able to rely on. Cyber Defence Operations plays an important role in protecting our customers, our data and the services they depend on.

We're proud to be recognised as a Great Place to Work® for the past two years, building on six consecutive years as one of the UK's Best 100 Companies to Work For. It's recognition we're proud of and a reflection of the supportive and collaborative culture we strive to create for our people.

What we offer 

• 27 days holiday, increasing with service + buy/sell scheme + bank holidays
• 8% Pension with matched contributions
• Discretionary bonus scheme
• Share schemes (including free shares and BAYE)
• Private healthcare and Dental plan
• Healthcare Cash Plan
• Enhanced family leave (subject to qualifying criteria)
• Travel and bike loan schemes
• Employee Assistance Programme

Life at AJ Bell

• Regular social events including summer and Christmas parties
• Learning and development opportunities tailored to you
• Casual dress code
• Friendly, supportive team environment

Our ways of working

At AJ Bell, our people are the heart of our culture. We believe in building strong connections by working together. That's why we offer a hybrid working model, where you'll spend a minimum of 50% of your working time from the office in either our Head office in Manchester or London Office. For new team members, the first 3 months will be spent full-time in the office to help you immerse yourself in our business and build valuable relationships with your colleagues.

Inclusion & diversity

We’re committed to creating an inclusive environment where everyone feels respected, supported and able to be themselves at work.

We welcome applications from all backgrounds and make hiring decisions based on skills, experience and potential.

Your application, reviewed by people

We believe great hiring starts with people. That's why every application is reviewed by a member of our Recruitment team, rather than screened by AI. It may take us a few days to get back to you, but please be assured that your application will be given the time and attention it deserves.

Agency information

This vacancy is being managed exclusively by our in-house Recruitment team. We are not partnering with recruitment agencies on this opportunity and will only accept applications submitted directly by candidates.