Here you will find helpful 3rd party information, information to help with advice and due diligence before you engage with a contractor.
The HSE are a great place to start when selecting a contractor, you can not only collect useful information on legal requirements but you can make sure your contractor isn't listed for breaking the law! The HSE are currently promoting the #dustbuster programme, they are also focusing on confined spaces silo and vessel cleaning contractors... Make sure your provider is working correctly!
http://www.hse.gov.uk/prosecutions/
IRATA Rope Access Technician check, here you can check the certification of any IRATA trained rope access workers on your site.