Thanks Ben,
After more Googling too, I've removed the console & found another blue wire on the new harness which was cable tied to it, so I missed it. Looks like I've just plugged the amp into my Pioneer harness. It has a piggy back blue wire which I stripped along with the one on the new harness, crimped a bullet connector on each on & hey presto, full signal & RDS data.
Just for those who are searching in the near future, it's an easy thing to miss & confuse you a little, it did me anyhow.