It depends on wether the program had subtitles when broadcast, no box can just add subtitles, not as far as I know, that would mean the sound going through a converter to display on the picture which would all add delays.
Pretty much everything has subtitles when first broadcast ( ok I'm sure there are some things without) so having them available for on demand sky movies, as an example, should be no problem but Virgin chose not to implement subtitles on the TV6 box for on demand. I was asking if they have chosen to implement it on the new 360 software.
Pretty much everything has subtitles when first broadcast ( ok I'm sure there are some things without)
I don't know the exact rule, but whether or not subtitles are required depends on a few factors like the audience share of the channel and how long the channel has been broadcasting. Major players eg BBC, ITV will be required to subtitle most programmes.
At some point we should be in a position to switch on live captioning for almost any programme that doesn't have its own subtitles - Google has this working pretty well in Android now.
I'm currently running Sky Q and TV 360 for comparison, and I can confirm that (for example) The Inbetweeners on-demand on Sky Q does have subtitles, and doesn't on TV 360. In fact, I've found very little on-demand content with subtitles on TV 360. This seems to be discriminatory/suboptimal for the hard of hearing.