OK going on with a bit of help from clemo and a diagram and comments from william I have done a bit more digging.
Decided to again check volts, I am getting a typical reading across the solenoid of 9 Volts, so not battery supply!
In the fuse box I found two fuses that would kill the volts across the pins. F33 or F41 both killed the volts.
Looks like F33 supplies the relay that powers the whole ECU through K46 to K22 (two relays) and F8 the 60 amp feed.
F41 supplies Y28 ?? and Y217 (turbo) so I would go for it being Y28 is the valve.
More digging and the fuse supplies are good, from the Green with Blue stripe wire I have is a very healthy battery supply to chassis, but not between the green and corresponding wire for the solenoid. So to me it looks like the negative side from the ECU is not there, so either still down to a duff ECU switching transistor or a bad joint.
A quick look near the foot pedals and removal of the ECU could be this weekend, possible bolted bracket that keeps it in place not sure if it is a simple release and pull out the ECU or if it is held in place some other way. Anyone taken the ECU out???
The single solenoid and the EGR valve.