ITV didn't totally abandon the South West, there's still the offices and edit suites at Truro, Plymouth, Exeter, Taunton and Weymouth as I understand it.
Where is ITV's Plymouth newsroom nowadays? I know for certain that they're not at Langage Science Park anymore, as I visited there recently. Assuming that I found the correct building (several of the industrial units there are nigh-on identical), it is now called "Westcountry House" and has various tenant companies that I've never heard of nor have any idea what industries they are.
Some road signs as you get near to Langage Science Park still say "Carlton TV" on them (and it can be clearly seen that even those are "labels" added onto the original signs, so must have something like "Westcountry TV" hidden underneath).
Similar situation with the original Central South building on an Abingdon industrial estate. At some point circa the 2011 ITV rebrand (I think?), the Meridian newsroom relocated to somewhere in Didcot. But, when I was last in Abingdon in 2013, nearby road signs still said "Central TV" (despite both the "Thames Valley" and "Meridian" rebrands having already happened by then).
However, the Abingdon industrial estate's own corporate signage (with a map and list resident companies) identified that building as "ITV Meridian" by then - Again, that still remained on the sign long after ITV had actually moved to Didcot, and the building was vacant.
The only ITV addresses that can be readily found through search engines or in phone directories etc, seem to be the London South Bank one and the Gas Street Birmingham one. They clearly don't want to publicise where most of their regional newsrooms are.