Funder policies make Open Access publishing compulsory
The policy of UK Research and Innovation (UKRI) is that outputs accepted for publication on or after 1 April 2013 have to be made openly accessible on the web. This applies to research that is fully or partially funded by UKRI. It covers peer-reviewed articles, conference papers and review articles but does not currently extend to monographs or book chapters, though this may change in the future. It also includes UKRI funded research by doctoral students even if they have already left the University.
The Wellcome Trust has a similar policy and it has been extended to cover monographs and book chapters resulting from grants awarded after 1 October 2013. The Wellcome Trust policy is about to change again from 1 Jan 2020.
Research England have announced that for the next Research Excellence Framework (REF2020) all journal articles and conference proceedings accepted for publication on or after 1 April 2016 will have to be openly accessible in a subject or institutional repository to be eligible for submission.
UKRI and the Wellcome Trust are not alone in demanding Open Access to research outputs. Funding body requirements can be viewed, for instance, via the SHERPA JULIET service.