Prepaid gold papers must also receive a liberal publishing licence (Creative Commons CC-BY), making the work free to text-mine or otherwise reuse, RCUK insists. An RCUK spokesperson says that the agencies hope in the future to insist that even work made free after six months has this liberal licence.
Essentially, this all brings into effect recommendations from the government-commissioned Finch report into open access, which advocated that authors pay publishers up front to make their work free to read. On the subject of delayed open access, however, the Finch report had suggested a 12-month publication embargo, much like the mandate now enforced by the US National Institutes of Health. And it was unclear about CC-BY publishing licences.
Finally, two research councils — the Arts and Humanities Research Council (AHRC) and the Economic and Social Research Council (ESRC) — will initially require papers to be made free only after 12 months. But that is only a transitional arrangement for the arts, humanities and social sciences, RCUK adds (a detailed explanation for this difference is posted here).