Hi Andy,
Despite it hunting away at idle the system goes into closed loop and stays there. From memory STFT stays around 0 and LTFT hunts around +/-4 for idle, at 2000rpm they both steadied around 0, sorry didn't write the values on my notes. Can't remember what the rear O2 was doing. Took loads of notes, did not unfortunately write everything down.
The customer has taken the car for the moment and is going to report back.