Had a call with the always lovely people at Toyota Online last week and they confirmed what
@PVGR said above.
They didn't seem to have much information themselves, but they told me there was no recall issue or problems with the car. Vehicles are instead being held so they can have more of a bulk launch then having them 'trickle out' to people one by one.
Discussing the chat on forums like this, the support guy said they had learnt a lot from this launch, particularly as to just how much nonsense/ rumours people come up with.
Now is the above true, is it covering for some kind of issue as previous posts have indicated? Who knows. But on the phone they saw no reason why my car, in derby since 5/7, wouldn't be with my dealer within a couple of weeks. It will then take the dealer approx 5 days to do whatever they have to do to it.
Hopefully this puts some minds at ease.