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3rd December 2025, Birmingham – Aristi, one of the UK’s leading providers of penetration testing and cyber security consultancy services, has today announced its acquisition by Limerston Capital’s cyber security platform business. The investment marks a significant milestone in Aristi’s growth journey and supports its ambition to continue setting the standard for high-quality, accredited cyber security services across the UK.
Aristi joins CyberCrowd, DigitalXRAID and IntaForensics as part of Xypher, the Limerston backed UK-based cyber services leader, with expertise in compliance, penetration testing, managed SOC, incident response, digital forensics and e-Discovery.
Aristi brings more than 17 years of specialist expertise, including a deeply accredited penetration testing capability as both a National Cyber Security Centre (NCSC) CHECK approved company and a CREST accredited provider. The business also offers a broad suite of cyber assurance and consultancy services, spanning information security governance, ISO 27001 consultancy, GDPR, DPO-as-a-Service, vCISO support, physical security assessments, and incident readiness exercises.
The acquisition strengthens the Limerston group’s expanding portfolio of managed cyber security, digital forensics, case management and e-Discovery services, called Xypher. With Aristi joining existing group companies, including CyberCrowd, DigitalXRAID and IntaForensics, customers benefit from enhanced end-to-end capabilities across cyber resilience, digital forensics, penetration testing, security consultancy, incident response, and operational technology (OT) security.
The combined expertise of Xypher allows it to support organisations across both public and private sectors, including those operating in critical national infrastructure, national security, housing, policing, healthcare, legal services, and energy. This strategic expansion further positions the group as a leading UK destination for specialist cyber and digital talent.
Harj Singh, Chief Executive Officer of Aristi, commented:
“This marks an exciting chapter for Aristi. For over 17 years, our mission has been to deliver trusted, high-quality cyber security testing and consultancy services that genuinely help our customers strengthen their defences. Joining Limerston Capital’s cyber platform gives us the investment, scale and wider capability to accelerate that mission even further. What attracted us most was the alignment of values; a focus on quality, integrity and long-term partnerships. We’re proud of what we’ve built so far, and with the wider group’s expertise, we look forward to expanding what’s possible for our customers and our team.”
João Rosa, Founding Partner at Limerston Capital, added:
“We’re delighted to welcome Aristi into our cyber security platform, Xypher. Their NCSC CHECK and CREST accredited penetration testing capability, paired with their strong governance and consultancy offering, makes them a highly complementary addition to the group. Aristi’s reputation, sector expertise, and relationship-driven approach perfectly align with our strategy to build a comprehensive and market-leading cyber security services provider. We look forward to partnering with Harj and the team to drive the next phase of growth responding to the ever-increasing demand for cyber security services.”
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About Limerston Capital
Founded in 2015 by James Paget, João Rosa and Martim Avillez, London based Limerston Capital pursues control investments in UK mid-market companies and seeks to create value through the firm’s buy-and-build and operationally focused model. The firm targets businesses with EBITDA of between £5 million and £15 million that have a solid value proposition, but have potential for operational improvements, have mispriced underlying returns on capital and provide opportunities for strategic repositioning via consolidation.
About Xypher
Xypher is a group of UK-based cyber security, digital forensic investigation and e-Discovery specialists with more than a decade of experience and extensive certified expertise, brought together to deliver industry leading end-to-end protection for organisations that demand excellence. From Managed Security Services and Incident Response to Digital Forensics, e-Discovery, Forensic Case Management, Compliance and Consultancy, we combine deep expertise with cutting-edge capability.
About Aristi
Aristi is one of the UK’s leading providers of penetration testing services with over 17 years of experience, supporting clients in the public and private sectors. We are a National Cyber Security Centre (NCSC) approved CHECK penetration test company and our testing services are also accredited by CREST. We provide a range of security testing services to help protect your cyber defences, as well as Information Assurance support and training.
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