In the past, anyone who wished to use a copyrighted work in the United Kingdom, but could not find the copyright holder to request permission, was unable to reproduce the work without violating copyright law. This changed as of October 29, 2014, when a new licensing scheme was introduced by the UK Intellectual Property Office that allows users to license copyrighted works for a fee, after making diligent efforts to locate the copyright holder(s). The revenue generated will be used to compensate the copyright holders should they ever come forward.
According to the announcement on gov.uk, "This ground breaking scheme builds on UK and international best practice and is the first to use an electronic application system and searchable register of the licences granted. It is being implemented alongside the EU Orphan Works Directive that enables cultural institutions to digitise certain orphan works in their collection and display them on their websites. Together these 2 schemes will help to display more of the UK’s cultural work at home and across Europe."
Read the announcement: "UK opens access to 91 million orphan works"