Castle Precision Engineering Services specialises in precision manufacturing for the defence, energy, and aerospace industries. The company produces complex components designed to meet the highly-specific demands of military application.
With £24m in turnover, up £4.9m on the previous period, the Glasgow-based company comes in at number ten on our list.
Terrafix supplies mission-critical IT and mobile communications hardware to emergency and security services, including parts of the defence sector.
The Stoke-On-Trent-based company, which was founded in 1983, has recently experienced exponential growth, seeing its turnover grow from £11.1m in 2022 to £28.3m in 2023. This scored the company a position in the Tussel Tech200 2023 cohort.
Cambridge-based CRFS manufactures and designs radio frequency (RF) intelligence equipment, used for applications in the regulatory, defence, aerospace and security industries.
The company — which has had eight patents granted across the UK, Europe, and the US — was acquired by US-based wireless tech firm Silvus Technologies in November 2020. And in 2024, CRFS posted a record-high turnover of £28.6m.
Concurrent manufactures high-performance single-board computers and plug-in cards, designed to operate in extreme weather conditions. Working closely with a number of industries, including military, aerospace, and communications, Concurrent has raised £8.27m in equity investment and in September 2023 acquired Phillips Aerospace.
The Colchester-based company, which was valued at £56m in its September 2023 fundraise, posted turnover figures of £31.7m according to its latest financial statement.
Sonardyne manufactures subsea technology for naval defence, specialising in underwater navigation, tracking, and surveillance. Its systems support maritime security and anti-submarine warfare with acoustic, optical, and sonar technology.
The company, which was founded in 1971 (and later incorporated in 1985), has received £1.69m worth of grants — including a £500k R&D grant from InnovateUK in 2017 — and has made five strategic acquisitions. And based on its latest financial statement in 2023, Sonardyne passed £100m in turnover for the first time.
Frazer-Nash Consultancy delivers advanced engineering and technology consultancy services to the defence sector.
With expertise in cybersecurity, energy resilience, and complex systems integration, the company supports military projects across land, air, sea, and cyber domains. Its work spans secure communications, autonomous systems, and defence infrastructure.
Frazer-Nash has two patents registered with seven patent authorities globally, and has received 15 grants, worth over £1.00m. The company’s latest turnover figures are £168m, up from £126m in its previous financial year.
Roke is a research and development company, working across a range of sectors including defence. Founded in 1956, the company designs and manufactures military solutions aiming to provide its clients with the information advantage on the battlefield.
With £998k of innovation grants awarded, and 458 patents granted by 29 global IP authorities, Roke is one of the most innovative defence tech companies on our list.
Ultra Electronics develops and manufactures software and products for use in the defence & aerospace, security & cyber, transport, and energy sectors.
With over 1,400 engineers and more than £150m spent on R&D to date, Ultra Electronics has had 95 patents granted across 17 authorities globally — making it one of the most innovative companies on this list. The business has also made one acquisition and spun out one company.
And with £287m in turnover, Ultra Electronics comes in at number three on our list of Defence Tech companies.
QinetiQ is a global defence technology company delivering research, engineering, and operational support to military and security agencies. Its expertise covers robotics, autonomous systems, advanced sensors, cybersecurity, and more.
In addition to developing integrated solutions for the military, QinetiQ also operates large-scale test and evaluation facilities, ensuring the UK’s defence capabilities remain operationally reliable.
With over 102 grants worth £28.1m awarded since 2002, the company has since spun out two companies and in 2018 acquired defence managed services company Inzpire. With almost £2b in turnover, Qinetiq eclipses almost every other company on our list.
BAE Systems is one of the most globally recognisable names in the defence industry. Its subsidiary, BAE Systems (Operations) Limited, is responsible for specific aspects of the company’s UK-based defence operations.
The company plays a critical role in national security, providing defence solutions in cybersecurity, artificial intelligence, and missile systems, in addition to further work in aerospace.
BAE Systems (Operations) Limited tops our list with over £6.97b in turnover, according to its latest financial statement.
