ONdigital / ITV Digital History
ONdigital launched in 1998 and was the world's first pay digital-terrestrial-television service, which later became ITV Digital, before collapsing in 2002.
ITV Digital timeline
ONdigital 1998 timeline (post-collapse)
This site is very much a work-in-progess, but there's plenty of valuable information available in the timeline.
Thanks to MediaBullet / DTTnews for providing their news archives to add to this site.