Sky have disabled subtitles on their On Demand service. Someone (I don't know them) is pushing this petition for Sky to buck up and sort out the subtitles.
As someone with hearing loss, I depend on subtitles for any audio. If companies are not pushed to provide it, they won't bother, and a big swathe of people like me will be excluded from a lot of content. It would be great if you would support this.
petition for Sky subtitles