CSIS expands its capabilities with cyber assurance and deepens its defence expertise, while i3Secure gains backing to continue growing, keeping its identity as it becomes part of one of Europe’s leading cyber security services players.
Copenhagen, Denmark, 28 October 2026: Allurity, a European cybersecurity group, has strengthened its position in the UK. CSIS Security Group (“CSIS”), one of its operating companies, has acquired i3Secure Ltd (“i3Secure”), a UK cyber security and information assurance consultancy.
Financial terms of the deal were not disclosed.
The deal is part of Allurity’s strategy to continue cementing its position as the leading European cybersecurity group. Including its latest acquisitions, Allurity now brings together nearly 900 cybersecurity specialists across Europe.
The acquisition supports CSIS’s strategy in a number of ways:
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It adds security assurance: checking and proving that systems meet required security standards. Demand for assurance is growing. Technology and threats keep changing, and organisations increasingly need to design security into their systems from the outset.
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It is a significant step forward in the defence, critical infrastructure, and public sector markets. Given the geopolitical situation, these sectors are key growth areas in the UK and across Europe.
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It brings CSIS closer to its goal of becoming the leading European intelligence-led cyber resilience partner for regulated, critical and security-minded organisations.
i3Secure is a close fit with CSIS’s business. Founded in Copenhagen in 2003, CSIS provides managed detection and response, incident response, security consulting and threat intelligence. The company already works in defence and national security, and in the public sector in both the UK and Denmark. The two companies’ services complement each other, particularly across cyber and physical security.
i3Secure works with highly regulated organisations in defence and the public sector. Its services include security assurance and accreditation, Secure by Design, security architecture and engineering, and governance, risk and compliance consultancy. Its consultants hold the highest UK government security clearances, and the company is certified to ISO 27001/ 9001, CE+ and DCC Level 0. Founded in February 2020, and employs 50 people.
Daniel Shepherd, CEO of CSIS Security Group, said: “CSIS and i3Secure have complementary expertise and share a client-focused culture. i3Secure’s assurance capabilities will enable us to increase our clients’ cyber resilience by further embedding security in their IT infrastructure. Defence, national security and public sector work are already familiar ground for us. i3Secure’s defence expertise expands that coverage, which is especially important at a time when the security outlook in Europe is changing rapidly. We’re looking forward to welcoming new colleagues and supporting i3Secure to build on the success already achieved.”
i3Secure, which will continue to execute its existing strategy and retain both its capability and sector focus, will continue to be led by Jason McAdam and Mike O’Regan as Managing Directors and the company’s existing Senior Leadership Team. Daniel Shepherd will Chair the company.
Existing customers of both companies will see no change to their contracts, contacts or service. In addition, i3Secure’s customers and partners can now draw on CSIS’s detection and response, incident response and threat intelligence services, as well as specialists across Allurity’s European network. In turn, CSIS customers gain access to i3Secure’s expertise in security assurance, accreditation and Secure by Design.
Mike O’Regan, Co-founder and Director of i3Secure, said: “We’ve built a business we’re incredibly proud of, supported by a fantastic team, strong client relationships and a reputation for delivering in some of the UK’s most demanding environments.
“Joining CSIS and the wider Allurity organisation is an exciting new chapter for i3Secure. Throughout our discussions, it was clear that we shared the same ambitions for the future. What particularly stood out was the commitment to helping us realise the full potential of the business while preserving the people, culture and specialist expertise that have made us successful. This creates opportunities to strengthen our capabilities, expand our reach across the UK and Europe, and build an even stronger future for our people and clients.”
