“Stop complaining and build”: Inside Defence Holdings’ software-first defence strategy

Defence Holdings is betting on AI, data, and sovereign technology as CTO Andy McCartney outlines a new defence doctrine built for speed

Modern defence is shifting from hardware to software. As cyber conflict, drone warfare, and information operations reshape global security, the advantage increasingly belongs to nations that can innovate faster — not just build bigger arsenals.

Defence Holdings PLC is a UK-listed defence technology company focused on building a software-led platform for modern military and security operations. Rather than manufacturing traditional hardware, it develops and acquires AI-driven tools for mission planning, logistics, cyber defence, secure communications, drone coordination, and protection of critical infrastructure. 

Defence Holdings recently appointed Andrew Roughan as CEO, formerly head of innovation hub Plexal, which oversees more than 700 startups and scaleups. While Roughan focuses on scaling the company’s commercial strategy, this interview centres on CTO Andy McCartney, who leads the design and deployment of Defence Holdings’ AI product stack.

Building the software layer of modern warfare

The company positions itself around the idea that future defence capability will increasingly depend on intelligent software, data, and automation, and is assembling a portfolio of technologies to help governments and allied organisations respond to cyber, information, and hybrid threats.

The edge-case engineer

The company’s software-first strategy is shaped heavily by McCartney’s background.

Andy McCartney brings nearly three decades of technology experience to Defence Holdings. A Belfast-born technologist, McCartney has built his career around developing systems ahead of mainstream demand — tools that organisations often recognise the value of only years later.

“My background’s pretty much online. I’ve been doing tech since I was 11 or 12,” he said.

Growing up in a rough area of Belfast, he spent long stretches teaching himself programming in public libraries. “That’s where I got a real passion for technology.”

He built his first computer at 12 and quickly gravitated toward technical problems others overlooked.

“I realised I was good at building the technology people said wasn’t needed — the 3 per cent nobody wanted. Then three years later, everyone says, ‘Can we please have that?’ That’s been my world: building the edge cases that later become essential.”

McCartney later served as CEO of Microsoft Ventures UK between 2013 and 2015, where he launched the company’s first venture innovation platform outside the United States and helped scale dozens of high-growth technology businesses. 

Defence as a natural fit

McCartney went on to found Whitespace, a Belfast-based company delivering generative AI into defence, the public sector and other highly regulated industries. Today, Whitespace platforms support frontline Ministry of Defence operations. His entry into defence, he says, was driven by both technical challenge and personal motivation.

“About 15 or 16 years ago, I was brought into defence and national security conversations around technology. I realised I was actually very good at it because it’s complex and fast-paced. It suited my attitude toward technology.”

He frames his work in direct terms:

“I’ve always been vocal about this — I really don’t like bad people. I grew up seeing bad people do bad things. Much of the technology I’ve built has been focused on stopping that. So defence felt like a natural fit.”

Alongside Defence Holdings and Whitespace, McCartney has founded SafetyTalks and Jam Pot Technologies and continues to serve as chief hacking officer at Tadaweb, with a focus on security, data systems, and high-risk operational environments. 

This background shapes how he sees Defence Holdings’ mission.

More capability, less money, greater urgency

Last year, the UK published the Strategic Defence Review. It calls on government, the armed forces, industry, and wider society to implement its 62 recommendations to ensure Britain can deter threats and respond effectively in a rapidly evolving security environment

The review advises a shift toward faster procurement, dual-use innovation, and deeper collaboration with startups. For younger defence companies, it effectively opens doors that were historically closed.

For McCartney, “It means developing more capability for less money, faster. We have less time and budget to solve complex problems quickly. That’s a massive attraction for me.”

According to McCartney, “the last time we truly operated at wartime speed was Bletchley Park. It was about solving impossible problems quickly, bringing in talent from the commercial and civil sectors, and working nationally to solve them.”

Ukraine has rewritten the rules of modern warfare

According to McCartney, Russia’s full-scale invasion of Ukraine fundamentally changed how modern warfare is understood.

“They didn’t have time to spin up high-end systems. War arrived in 24 hours. They had to innovate immediately,” he said.

Without access to Western intelligence infrastructure, Ukrainian forces relied on low-cost hardware, commercial platforms and open data — constraints that forced rapid experimentation.

“Jeopardy creates high-quality solutions because failure has consequences.”

Rather than deploying multi-million-dollar systems, Ukraine adapted consumer technology at scale. Cheap drones are now capable of destroying tanks worth up to €1 million — a cost imbalance that McCartney says “rewrites doctrine.”

“Ukraine isn’t spending $10 million per system. They’re bolting functionality onto consumer drones and integrating them into the kill chain. That mindset is powerful.”

The lesson, he argues, extends well beyond the battlefield. NATO countries must rethink how they design and procure defence capabilities. Ukraine isn’t just a war story — it’s a preview of how modern defence will operate in the future.

“For every solution you create, a hundred new problems appear. Meanwhile, you have institutions wrapped in legacy procurement systems that weren’t built for this speed. That’s the seismic shift.”

Rebuilding domestic defence capability

Defence Holdings positions itself as part of a broader push toward sovereign capability in UK defence technology. The company aims to reduce reliance on foreign-built systems by accelerating the development of domestic alternatives.

“When you buy externally, the money leaves your economy, and you’re not part of the development cycle,” he said.

“You don’t understand the solution as deeply because you didn’t build it.”

He argues that the UK’s dependence on non-sovereign technology is often driven more by speed than by preference. Defence agencies frequently turn to foreign suppliers because domestic suppliers have struggled to deliver at the pace operational needs demand.

“The UK often has no choice but to buy non-sovereign technology because no one has provided alternatives at the speed required,” McCartney said.

“Defence Holdings exists to change that.”

The company’s strategy is to work with smaller technology partners and hyperscale infrastructure providers to deliver sovereign applications faster — giving UK defence agencies greater control over both the technology stack and its long-term evolution.

Why smarter systems beat bigger arsenals

What Ukraine exposed, McCartney argues, is not just the importance of readiness, but the central role of data in maintaining it. Modern defence capability, he says, depends less on raw firepower and more on how effectively information is processed and acted upon. Yet he believes the long-standing assumption that “data equals power” can itself become an obstacle.

“I once heard a senior military leader say, ‘The last thing I need is more data.’ That terrified me,” he said. “Amazon, Microsoft, Apple — they want more data. It sharpens execution. If you can’t use data, your systems are broken.”

For McCartney, the issue is not volume, but interpretation. Data, he argues, removes institutional bias. “If decisions aren’t data-driven, they’re opinion-driven,” he said.

“If you ask the army, navy and air force how to defeat an enemy, each argues for their domain. AI looks at the problem neutrally. Its strength is analysing data without institutional bias.”

The lesson reinforced by Ukraine, he says, is clear: superiority will increasingly come from intelligent systems rather than sheer scale

. “Ukraine proved the solution isn’t more tanks. It’s smarter systems.”

A system finally starting to move

McCartney advises that cultural change in the UK, somewhat insulated from the battlefields of Ukraine, is possible.

He advises:

“Demonstration beats argument. Instead of waiting a year for approvals, I go directly to the person with the problem. We build fast. Then we come back and demonstrate the working solution.”

Once people see it functioning, resistance disappears. Then, the only barrier left is process. Suddenly, onboarding documents shrink. Procurement timelines compress. Senior leadership now has proof they can use to push internal reform.

“We’re not waiting for defence to fully transform before engaging. We’re engaging now and helping accelerate that transformation,” he asserts.

The shift from hardware to information warfare

Defence Holdings is seeing the most traction in real-time learning systems that analyse operations and continuously improve them. 

According to McCartney, “Information warfare is huge: misinformation, cyber, psychological operations. A teenager with tools can destabilise a public figure faster than institutions can respond. Encryption and redundancy matter because communication infrastructure is converging.”

He also shares my interest in spacetech as critical to defence, asserting, “Ukraine showed commercial satellites can outperform traditional military systems. That changes assumptions.”

In terms of UK readiness in defencetech, McCartney admits, “a year ago I’d have been cautious. Now I’m encouraged.” He sees commitments made in early 2025 are turning into reality, noting:

“For an organisation as regulated as defence, that pace is impressive. It reminds me of Microsoft’s transformation under Satya Nadella. Cultural change takes time, but once it starts, it compounds.”

“Stop complaining and build”

McCartney advises startups interested in defence/dual defence to jump in:

“History is being written, and this is a historic window. The blueprint doesn’t exist yet. In three years, it will.

Stop complaining and build.

Right now, a small team can compete with giants.

If six out of ten attempts succeed, you’re ahead of everyone who tried none.

Defence Holdings isn’t a traditional prime contractor. We’re a bridge. If you’re solving real problems, talk to us.”