About Us

NSL Checking, a business unit of Marston (Holdings) Ltd, provides unrivalled expertise and a comprehensive range of services to meet the identity checking, document verification and background screening requirements of large public and private sector organisations as well as small commercial enterprises. Harnessing the world’s most advanced validation technologies, the company also has a large team of highly experienced vetting officers as well as direct links with the Home Office, Police Service and fraud agencies. Consequently, it provides customers with a consistent, reliable and highly responsive service to minimise risks and ensure compliance with ever-changing legislation and identity check regulations.

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Advanced validation technologies have an important role to play. But, they are not a panacea. That’s why we have a large team of highly experienced vetting officers, with up to date knowledge and training on the latest legislative and procedural requirements and fraud identification techniques to provide our customers with reassurance and complete peace of mind. With further legislative changes likely to result from Brexit implementation, it’s significant that we receive advance notification of any changes to Home Office guidance and procedures. Our Technical Director is also directly involved in two Home Office liaison groups concerning illegal migrant working and the employment of migrant workers.



Our robust checking processes and services have been designed to be repeated hundreds of thousands of times with consistent, predictable and reliable outcomes. As well as accreditation to ISO 9001, 14001 and ISO 27001 and adhering to a policy of continuous improvement, we have strict disciplines to ensure all our processes take full advantage of cutting edge validation technologies and are aligned with the latest legislation at all times.

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NSL enjoys highly effective partnerships with Keesing Technologies and The Access Group. Keesing provides the world’s most comprehensive library of identity documentation and are a respected and authoritative source for document verification. The Access Group provides the Access Screening platform. NSL chose to partner with Access to ensure that NSL can provide its clients with a cost-effective, scalable service across a range of identity, background screening and vetting checks. The Access Screening platform when combined with NSL’s vetting officer expertise, provides an unbeatable combination of people, process and technology in a managed service.

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With an experienced team of dedicated vetting officers, the latest software systems and a comprehensive identity document reference database, NSL continues to be a trusted partner of some of the most well recognised and respected organisations throughout the public and private sectors.

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Part of the NSL Group

NSL Checking is part of the NSL Group which delivers highly regulated services to over 20 million citizens on behalf of 180 organisations – from Councils and government departments and The National Health Service to airports, major retailers and small businesses. With over 4,500 employees working from 250 bases around the UK, the NSL Group has more than twenty specialist service areas covering areas such as enforcement and licensing, neighbourhood and community services, design and consultancy, people development and passenger transport.