OK if anyone is still interested after all this, here's the latest !

Got a new CA3140 from Maplins (2 actually just in case !) and replaced the one that I had put in the wrong way round and desoldered/soldered.

Connected it all up and ...................still no FM

It seemed that connecting the aerial made no difference, which made me suspicious, and on inspection, the RF lead, having been removed so many times from the case had broken where it joins the PCB.

I resoldered the RF lead and (at last) I had full FM reception including RDS

I've just re-installed it in the car and have still got excellent FM although the AM is a bit flaky. It was fine on the bench so maybe the VW amplified aerial is causing the problem. I'd be interested to know if any other VW owners have the same problem with AM.

Anyway FM is now 100% and, apart from the odd football match on Radio 5, I can't see me needing AM anyway, so I'm 99% happy

Thanks for the help on this, and thanks to Patrick for a great product - my problems in no way reflect badly on your instructions - I'm just an idiot !

Geoff