This question was answered on 3rd May 2016
The provision of access services on video on demand content has increased in recent years, according to the 2015 Authority for Television on Demand report which can be found here:
http://stakeholders.ofcom.org.uk/binaries/broadcast/on-demand/access-european/AS_survey_report_2015.pdf. The evidence in this report is supported by dialogue with broadcasters, content providers and platform operators, who fed back to the Department of Culture, Media and Sport in Autumn 2015.