[Stooky Bill]

GMTV still passed through the regional centres as they did the news bulletins, but my understanding but via the news studios who essentially opted out. 

I do seem to remember teletext vanishing during the regional news bulletins, so that would explain that, the teletext wouldn't pass through the studios, that potentially could have disappeared during local bulletins 

Teletext (capital T) was inserted at the transmitters so it shouldn't have done. 

The only teletext (lower case t) that passed through the TV stations were the ancillary services on p600 and subtitles. During GMTVs hours p600 was GMTV Text. That potentially could have disappeared during bulletins depending on how they were configured