ITV News did used to come from Studio 2 for a long while, but they moved back to Studio 1 some time ago. PCR1 controls Studio 1 and PCR2 controls Studio 2. The problem is that PCR2 is the backup ITV News control room so it can't remain as the 5 News control room. It will be until a new control room is built for 5 News shortly. The equipment for this will be brought from the Northern & Shell building.
The last time 5 News was based at GIR, it used PCR4, which now no longer exists. Back then, PCR2 was on the ground floor and was the control room for Studio 4, the ITV London studio.