[Humphrey Hacker]

How on earth can you be so certain? It was a hostile race to become the biggest. Even ignoring Thames, different calls at different moment could've led to LWT becoming a major power, or UNM becoming bigger than they were... perhaps Granada would've ended up as the minnow steadfastly refusing to sellout.

Thames didn't continue because they were a staunch independent, they continued because Thorn EMI and BET sold what was left of them off to Pearson. Perhaps that would have happened anyway and Pearson would have proceeded to buy up whichever other Channel 3 franchises were available to them.

Or perhaps Carlton would have bought the Channel 3 operation, sold the production business to Pearson and the rest would have been exactly the same.

There is no way of knowing, you can't remove one critical item from a chain of events and conclude with certainty the outcome would definitely be the same; even if "the outcome" in this case is a single ITV plc.

This article from Transdiffusion speaks of an "alternate" ITV:
transdiffusion.org