[Technologist]

Not wanting to divert too much from 30 year of itv -
But one effect of the new contractors was the weakening of Engineering coordination between companies...
so things were not rolled out across all companies/ regions.
for instance Carlton just transmitted PDC code which said "use the VCRs clock"
which was not really much good - but lit the PDC led on the front of the VCR!!!!!

The concepts of Additional services = Oracle/Teletext ltd, and also Datacast etc
and Ancillary Services (programme related) - "4tel etc"  subtitles (Access services)
Recording control etc  (and PresFax, Adavails etc) ...  were very important in the formation of Digital Tv services.
The UK was unique in splitting its Teletext services into these groupings... and sub groupings 

BTW Westward did some interesting stuff ... but was "below the radar"
while 4tel was not!
Teletext costs money run -  the only Teletext company which even really made a Profit
was Teletext Ltd who for two years paid more tax that the total Ceefax budget!
Oracle was also profitable but not to that extent! 
So most Itv companies were not really that interested.