JJ
jjne
Drama being one of the most expensive forms of TV, it is unlikely they would have made a drama without the backing from the Big 5 though.
It's rare but it did occasionally happen. I can think of at least two occasions when a Tyne Tees, a small company, produced local drama -- once in 1990 (a co-production with TVS that I do not recall the name of), and once in 1997 (Quayside -- a soap which was co-produced with YTV).
Other stations doubtless did this as well from time to time. But the point is; in its local area any ITV station could (and technically still can) produce and show whatever it pleased to its own audience, and at whatever time it chose.