Hiring for defence roles comes with a problem most job boards weren’t built to solve. You need candidates who hold, or can obtain, security clearance. You’re often hiring for niche disciplines like systems engineering, cyber security, or naval architecture, where the qualified pool is small to begin with. And the standard channels, built for volume hiring across every industry, tend to return applications that look right on paper and fall over at the vetting stage.
This is a practical look at the main options for advertising defence and security vacancies in the UK, what each one is actually good at, and where the trade-offs sit.
General Job Boards (Indeed, Reed, Totaljobs)
General boards give you reach. Millions of monthly visitors, established SEO authority, and low cost per posting. For high-volume, low-clearance roles like warehouse or logistics support, they can work well enough.
The weakness shows up with clearance-dependent roles. These boards have no way to filter for SC, DV, or BPSS status, so every applicant looks the same until you’ve screened them manually. Hiring managers commonly report high application volumes but low qualified-to-interview ratios for cleared roles specifically, because the platform has no mechanism to pre-filter for the one criterion that matters most.
Cost per hire on general boards is low in isolation. Factor in the recruiter or hiring manager hours spent screening unqualified applicants, and the real cost climbs quickly for anything requiring active clearance.
LinkedIn’s strength is passive candidate reach. Cleared engineers who aren’t actively job hunting still maintain a profile, and LinkedIn’s targeting lets you reach people by job title, employer history, and location. For senior or hard-to-fill roles where you’re sourcing rather than posting and waiting, it earns its cost.
The gap is discovery. LinkedIn job posts compete in a general feed alongside every other industry, and clearance status isn’t a searchable or filterable field on the platform. A cleared candidate actively looking for their next role has no way to search specifically for vetted defence vacancies. LinkedIn also charges per click or per day live, and costs scale up fast for competitive roles, since you’re bidding against every other employer targeting the same job titles.
Recruitment Agencies
Agencies solve the screening problem directly. A good defence-sector agency already has a warm network of cleared candidates and won’t waste your time with unqualified applications. For urgent, senior, or highly specialised hires, particularly DV-cleared roles where the candidate pool is genuinely small, this can be the fastest route to a shortlist.
The cost is significant. Agency fees typically run at 15 to 25 percent of first-year salary, which on a £70,000 systems engineer role is £10,500 to £17,500 per hire. For a single urgent vacancy that’s often justified. For ongoing or volume recruitment across multiple roles, the economics stop making sense, and many defence employers end up running agencies alongside direct advertising rather than instead of it.
Specialist Defence Job Boards
Specialist boards trade some of the raw reach of Indeed or LinkedIn for relevance. Every visitor arrived specifically looking for defence, aerospace, cyber, or national security work, which changes both the volume and quality of applications.
The clearance-filtering point matters most here. A board that categorises roles by clearance level (BPSS, SC, DV) the way CareersInDefence does means a candidate who already holds SC clearance can search only for roles they qualify for, and your listing only reaches people who can realistically start the vetting-adjacent parts of the process straight away. That cuts down the screening overhead that makes general boards expensive in practice, even when the sticker price per posting is lower.
The trade-off is audience size. A specialist board will never match Indeed’s total monthly visitors. For most defence roles, that’s the right trade, since the relevant pool of cleared or clearable candidates was always a small fraction of Indeed’s traffic to begin with.
Direct Sourcing and Employer Career Pages
Posting directly to your own careers page costs nothing beyond the time to maintain it, and it’s essential for capturing candidates who already know your company. On its own, it rarely generates enough new applicant volume for active recruitment, since it depends on candidates already searching for you by name rather than discovering you.
Which Option Actually Makes Sense
None of these replace each other completely, and most defence employers end up running two or three in parallel depending on the role.
For urgent, senior, or DV-cleared hires where speed matters more than cost, an agency is often worth the fee. For passive sourcing against a specific target list, LinkedIn earns its spend. For steady-state hiring across engineering, cyber, and project management roles at SC or BPSS level, a specialist board tends to give the best ratio of qualified applicants to cost, because the clearance filtering does the first round of screening before a CV ever reaches you.
The mistake worth avoiding is treating general job boards as a default for every role. They’re built for volume, not for a small, clearance-dependent talent pool, and the hours spent screening unqualified applicants are a real cost even when the posting itself was free.
Advertising a defence or security vacancy? See how CareersInDefence indexes roles by clearance level and discipline to connect you with the right candidates.