Thanks Boris that is very useful.
This morning I spoke firstly to CMC. After some discussion at their end, it now appears that CMC accept that, although the California is registered as an MPV, there is no problem with them insuring it. They have clearly encountered the problem several times and adapted accordingly. However, when I sought clarification of their new for old policy, the response was more worrying. It appears that they would consider the T6.1 to be a new model. So in the now almost certain event that a ‘like for like‘ new T6 model was was not available, their settlement figure would be the market value at the time, ie a lower figure.
I then spoke to VW about their 12 months free insurance and confirmed that it provided new for old cover. When questioned on the T6 replacement by the T6.1, after discussion at their end, I was advised that it would be by the closest available model. So in the likely unavailability of a T6 the replacement would be a T6.1.
It looks as though I will be taking up the free 12 months insurance offer from VW.
NB I have none of this in writing.