Since i posted the last message, i have done some additional testing and found that the wiring to the ECU from the first oxygen sensor checks out, and the sensor is providing acceptable voltages to the ECU.
This is not being recognised by the scanner, the scanner is reading 0V at all times, reading both sensors on EOBD 2.
However, the secondary sensor is not providing any voltage at the ECU as the first sensor is. I have ordered a second sensor.
I also found that the ECU earths (green and yellow) on the gear box had a badly corroded connector- so I have soldered in a new ring terminal.
Thanks again for your comments on this one, and i will post an update once i have got the secondary sensor fitted.