Re subtitles on teletext.
Weren't the subtitles on the BBC originally produced by BBC Scotland? I remember their caption at the end reading "Subtitles by Callum Short, BBC Scotland - 1989", and then to BBC Broadcast, Red Bee Media and finally and currently Ericsson?
The ITV subtitles were listed as Oracle before ITFC and today Deluxe.
Channel 4's were 4-Tel before Subtext, Intelfax and BBC Broadcast/Red Bee/Ericsson.
As far as I know Channel 5 were originally 5text before going to ITFC, Red Bee and now Ericsson.
Regional subtitles on ITV were listed as ITFC South or North depending on the region apart from Channel TV who did their own, as did STV and UTV.
RTÉ on the other hand just pinched theirs from the original broadcaster. I remember watching Grease on RTÉ years ago and the subtitles read something like: "Original subtitles by BBC Scotland, edited by ITFC and retyped by RTÉ." or something along those lines.
"Stop touching Dot's pussy - you don't know where it's been!" (Honey Mitchell, EastEnders)